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Case Studies (325)

Sunday, 05 March 2017 16:28

Mediterranean Basin

Written by Juli Pausas

Mediterranean Basin

Main Contributors:

Juli Pausas

Other Contributors:

Summary

In the European region of the Mediterranea Basin there was an abrupt fire regime shift in such a way that fires increased in annual frequency (doubled) and area burned (by about an order of magnitude). The main driver of this shift was the increase in fuel amount and continuity due to rural depopulation (vegetation and fuel build-up after farm abandonment) suggesting that fires were fuel-limited previous to the shift. Climatic conditions are poorly related to wildfire activity during the pre-shift period and strongly related during the to post-shift period, suggesting that fires are currently less fuel limited and more drought-driven than before. Thus, the fire regime shift implies also a shift in the main driver for fire activity. This shift was dated in the 1970s in Spain but this may varies in other countries.




Type of regime shift

  • Fire regime shift

Ecosystem type

  • Mediterranean shrubs (egFynbos)

Land uses

  • Small-scale subsistence crop cultivation

Spatial scale of the case study

  • Sub-continental/regional (e.g. southern Africa, Amazon basin)

Continent or Ocean

  • Europe

Region

  • Mediterranean Basin

Countries

  • Spain
  • Greece

Locate with Google Map

Key References

  1. Pausas J.G. & Fernández-Muñoz S. 2012. Fire regime changes in the Western Mediterranean Basin: from fuel-limited to drought-driven fire regime. Climatic Change 110: 215-226.
  2. Pausas J.G. & Fernández-Muñoz S. 2012. Fire regime changes in the Western Mediterranean Basin: from fuel-limited to drought-driven fire regime. Climatic Change 110: 215-226. http://dx.doi.org/10.1007/s10584-011-0060-6

Citation

Juli Pausas. Mediterranean Basin. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-03-09 16:22:33 GMT.
Friday, 08 January 2016 16:52

Vegetation regime shifts in Yamal-Nenets

Written by Hanna Ahlström

Vegetation regime shifts in Yamal-Nenets

Main Contributors:

Hanna Ahlström, Jonas Gren, Ashley Perl, Fernando Remolina, Fernando Remolina, Ashley Perl, Jonas Gren

Other Contributors:

Summary

The Yamal-Nenets social-ecological system comprises about 5000 nomadic reindeer herders and 300 000 semi-domestic reindeers, moving with the seasons in 21 different brigades from the southern tree limit up north, across the Arctic tundra. Shrub encroachment has been observed during the last three decades, but has been controlled by reindeer grazing. These changes have produced two regime states: shrubland without reindeer herding, and open land with reindeer herding. The first regime is mainly caused by temperature increase, which has produced warmer winters, summers and extended growing seasons. These temperature changes have altered the controlling feedbacks of the tundra, such as slow growth of shrubs, microbial activity, and decomposition litter rates. This regime is hence seen as the undesirable regime for the Yamal-Nenets social-ecological system.

Type of regime shift

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Land uses

  • Extensive livestock production (natural rangelands)

Spatial scale of the case study

  • Local/landscape (e.g. lake, catchment, community)

Continent or Ocean

  • Asia
  • Europe

Region

  • Yamal Peninsula, Northwest Siberia

Countries

  • Russia

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. Aune, S., Hofgaard, A., & Söderström, L. 2011. Contrasting climate- and land-use-driven tree encroachment patterns of subarctic tundra in northern Norway and the Kola. Canadian Journal of Forest Research, 41(3), 437–449.
  2. Bråthen, K. A., Ims, R. a., Yoccoz, N. G., Fauchald, P., Tveraa, T., & Hausner, V. H. 2007. Induced Shift in Ecosystem Productivity? Extensive Scale Effects of Abundant Large Herbivores. Ecosystems, 10(5), 773–789.
  3. Couture, T., and Gagnon, Y. 2010. An analysis of feed-in tariff remuneration models: Implications for renewable energy investment. Energy policy 38 (10), 955-965. Degteva, A., & Nellemann, C. (2013). Nenets migration in the landscape: impacts of industrial development in Yamal peninsula, Russia. Pastoralism: Research, Policy and Practice, 3(1), 15.
  4. Forbes, B. C., Stammler, F., Kumpula, T., Meschtyb, N., Pajunen, A., & Kaarlejärvi, E. 2009. High resilience in the Yamal-Nenets social-ecological system, West Siberian Arctic, Russia. Proceedings of the National Academy of Sciences of the United States of America, 106(52), 22041–8.
  5. Golovatin, M. G., Morozova, L. M., & Ektova, S. N. 2012. Effect of reindeer overgrazing on vegetation and animals of tundra ecosystems of the Yamal peninsula, Czech Polar reports, 2(12), 80–91
  6. Grace, J., Berninger, F., & Nagy, L. 2002. Impacts of Climate Change on the Tree Line. Annals of Botany, 90(4), 537–544.
  7. Henden, J.-A., Yoccoz, N. G., Ims, R. a, & Langeland, K. 2013. How spatial variation in areal extent and configuration of labile vegetation states affect the riparian bird community in Arctic tundra. PloS one, 8(5),1-10.
  8. Kullman, L. 2002. Rapid recent range-margin rise of tree and shrub species in the Swedish Scandes. Journal of Ecology, 90(1), 68–77.
  9. Kumpula, T., Forbes, B. C., Stammler, F., & Meschtyb, N. 2012. Dynamics of a Coupled System: Multi-Resolution Remote Sensing in Assessing Social-Ecological Responses during 25 Years of Gas Field Development in Arctic Russia. Remote Sensing, 4(12), 1046–1068.
  10. Kumpula, T., Pajunen, A., Kaarlejärvi, E., Forbes, B. C., & Stammler, F. 2011. Land use and land cover change in Arctic Russia: Ecological and social implications of industrial development. Global Environmental Change, 21(2), 550–562.
  11. Macias-Fauria M, Forbes BC, Zetterberg P, Kumpula T. 2012. Eurasian Arctic greening reveals teleconnections and the potential for structurally novel ecosystems. Nature Climate Change 2, 613–618.
  12. Myers-Smith, I. H. 2007. Shrub Line Advance in Alpine Tundra of the Kluane Region: Mechanisms of Expansion and Ecosystem Impacts. Arctic, 60(4), 447-451.
  13. Olofsson, J., Oksanen, L., Callaghan, T., Hulme, P. E., Oksanen, T., & Suominen, O. 2009. Herbivores inhibit climate-driven shrub expansion on the tundra. Global Change Biology, 15(11), 2681–2693.
  14. Strum, M., Douglas, T., Racine, C., & Liston, G. E. 2005. Chagning snow and shrub conditions affect albedo with global implications. Journal of Geophysical Research, 110, 2156-2202.
  15. Sturm, M., Schimel, J., Michaelson, G., Welker, J. M., Oberbauer, S. F., Liston, G. E., … Romanovsky, V. E. 2005. Winter Biological Processes Could Help Convert Arctic Tundra to Shrubland. BioScience, 55(1), 17-26.
  16. Tape, K., Sturm, M., & Racine, C. 2006. The evidence for shrub expansion in Northern Alaska and the Pan-Arctic. Global Change Biology, 12(4), 686–702.
  17. Wal, V. D. R., 2006. Do herbivores cause habitat degradation or vegetation state transition ? Evidence from the tundra. Oikos, 114:1, 177–186.
  18. Walker, D. A., Forbes, B. C., Leibman, M. O., Epstein, H. E., Bhatt, U. S., Comiso, J. C., … Yu, Q. 2011. Eurasian Arctic Land Cover and Land Use in a Changing Climate. (G. Gutman & A. Reissell, Eds.), 207–236.
  19. Walker, M. D., C. Wahren, H., Hollister, R. D., Henry, G. H. R., Ahlquist, L. E., Alatalo, J., … Wookey, P. A. 2006. Plant community responses to experimental warming across the tundra biome PNAS, 103(5), 1342-1346.
  20. Yu, Q., Epstein, H. E., Walker, D. a, Frost, G. V, & Forbes, B. C. 2011. Modeling dynamics of tundra plant communities on the Yamal Peninsula, Russia, in response to climate change and grazing pressure. Environmental Research Letters, 6(4),1-12.
  21. Zeng, H., Jia, G., & Forbes, B. C. 2013. Shifts in Arctic phenology in response to climate and anthropogenic factors as detected from multiple satellite time series. Env. Rev. Lett., 8, 1–12.
  22. Zimov, A. S. A., Chuprynin, V. I., Oreshko, A. P., Iii, F. S. C., & Reynolds, J. F. 1995. Steppe-Tundra Transition : A Herbivore-Driven Biome Shift at the End of the Pleistocene American Naturalist 146(5), 765–794.

Citation

Hanna Ahlström, Jonas Gren, Ashley Perl, Fernando Remolina, Fernando Remolina, Ashley Perl, Jonas Gren. Vegetation regime shifts in Yamal-Nenets. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-02-08 10:45:18 GMT.

Collapse of Newfoundland cod fisheries, Northwest Atlantic

Main Contributors:

Roweena Patel, Kate Williman, Viveca Mellegard, Philipp Siegel, Kate Williman, Viveca Mellegard, Philipp Siegel

Other Contributors:

Reinette (Oonsie) Biggs, Juan Carlos Rocha

Summary

The Newfoundland cod fishery is a social-ecological system that is centered upon Arctic cod, Gadus morhua populations in the waters off Newfoundland and Labrador in the Northwest Atlantic. High fishing pressure, along with regional climatic variability that delivered colder water to the Northwest Atlantic ocean, disturbed the cod spawning grounds and led to a dramatic cod fishery collapse. Recovery in the fishery has been minimal and very slow, partly because cod population growth will take time to replenish the amount of stock that was lost. This regime shift has impacted ecosystem services by reducing the food source both at the local and the global scale. There has also been a loss of income from cod fishing at the local scale that affects human wellbeing among Newfoundland fishers and the communities relying directly and indirectly on the fishing industry. Actions taken to restore the cod regime shift includes banning of the commercial fisheries in the Northwest Atlantic, tighter regulations and dock-side monitoring programs.

Type of regime shift

Ecosystem type

  • Marine & coastal

Land uses

  • Fisheries

Spatial scale of the case study

  • Sub-continental/regional (e.g. southern Africa, Amazon basin)

Continent or Ocean

  • North America
  • Atlantic Ocean

Region

  • Northern North Atlantic

Countries

  • Canada

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

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  15. Dutil, J.-D., & Brander, K. (2003). Comparing productivity of North Atlantic cod (Gadus morhua) stocks and limits to growth production. Fisheries Oceanography, 12(4/5): 502–512.
  16. Eide, A., Heen, K., Armstrong, C., Flaaten, O., & Vasiliev, A. (2013). Challenges and Successes in the Management of a Shared Fish Stock–The Case of the Russian–Norwegian Barents Sea Cod Fishery. Acta Borealia,30(1), 1-20.
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  20. Haedrich, R. L., & Hamilton, L. C. (2000). The fall and future of Newfoundland's cod fishery. Society & Natural Resources, 13(4), 359-372.
  21. Hamilton, L. (2010). Footprints: Demographic effects of outmigration. Migration in the Circumpolar North: Issues and Contexts. L. Husky and C. Southcott (Eds). Edmonton, Alberta: Canadian Circumpolar Institute, 1-14.
  22. Hamilton, L. C., & Butler, M. J. (2001). Outport adaptations: Social indicators through Newfoundland's cod crisis. Human Ecology Review, 8(2), 1-11.
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Citation

Roweena Patel, Kate Williman, Viveca Mellegard, Philipp Siegel, Kate Williman, Viveca Mellegard, Philipp Siegel, Reinette (Oonsie) Biggs, Juan Carlos Rocha. Collapse of Newfoundland cod fisheries, Northwest Atlantic. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-02-07 12:18:06 GMT.
Monday, 08 June 2015 19:53

Arctic mobility

Written by Cláudia Florêncio

Arctic mobility

Main Contributors:

Tove Björklund, Cláudia Florêncio, Rawaf al Rawaf, Tove Björklund, Rawaf al Rawaf

Other Contributors:

Juan Carlos Rocha

Summary

Due to anthropogenic climate change and diminishing navigable ice, the Inuit’s mobility and available livelihoods are currently undergoing a regime shift. Inuit communities are increasingly relying on both wage employment and traditional subsistence harvesting, indicating we are probably witnessing the transition between these two livelihood regimes. The main drivers for this transition are anthropogenic climate change and increasing access to store-bought goods through trade and import. The necessity to secure access to food (either traditional or store-bought), and the erosion of traditional knowledge and shifting cultural norms are the key processes impacted by these drivers, as evidenced by the state of human well-being and ecosystem services in Inuit communities today.

Type of regime shift

Ecosystem type

  • Tundra
  • Polar

Land uses

  • Fisheries

Spatial scale of the case study

  • Sub-continental/regional (e.g. southern Africa, Amazon basin)

Continent or Ocean

  • Europe
  • North America
  • Arctic Ocean

Region

  • Arctic Region

Countries

  • Russia
  • Sweden
  • United States
  • Canada
  • Denmark
  • Finland

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. Aporta, C. (2004) Routes, trails and tracks: trail breaking among the Inuit of Igloolik. Etudes/Inuit/Studies 28:9–38.
  2. Dicks, L. Arctic Climate Issues (2011) Changes in Arctic Snow, Water, Ice and Permafrost. Arctic Monitoring and Assessment Programme (AMAP).
  3. Ford, J. (2008) Vulnerability of Inuit food systems to food insecurity as a consequence of climate change: a case study from Igloolik, Nunavut. Regional Environmental Change. Springer.
  4. Ford, J. et al (2010) Climate change policy responses for Canada’s Inuit population: The importance of and opportunities for adaptation. Global Environmental Change 20, issue 1: p.177–191.
  5. Gearheard, S. Matumeak, W. Angutikjuaq, I. Maslanik, J.A. Huntington, H.J.L. Matumeak, D.G.T. Barry, R.G. (2006) It’s not that simple: comparison of sea ice environments, observed changes, and adaptations in Barrow Alaska, USA, and Clyde River, Nunavut, Canada. Ambio 35:203–211. doi:10.1579/0044-7447(2006)35 [203:INTSAC]2.0.CO;2
  6. Hastrup, K. (2009) Arctic hunters: climate variability and social flexibility. Chapter 12 in Hastrup, Kirsten. The Question of Resilience, Social Responses to Climate Change. The Royal Danish Academy of Science and Letters. 362p.
  7. Hastrup, K. (2013) The nomadic landscape: People in a changing Arctic environment. Geografisk Tidsskrift-Danish Journal of Geography, 109:2, 181-189, DOI: 10.1080/00167223.2009.10649606
  8. Hinzman, L.D. et al (2005) Evidence and Implications of Recent Climate Change in Northern Alaska and Other Arctic Regions. Climatic Change 72: 251–298 DOI: 10.1007/s10584-005-5352-2
  9. Huntington, H. & Fox, S. (2007) ACIA Secretariat and Cooperative Institute for Arctic Research University of Alaska Fairbanks, chapter 3, accessed on 2014-11-25 http://www.acia.uaf.edu/PDFs/ACIA_Science_Chapters_Final/ACIA_Ch03_Final.pdf
  10. ICC (2008) The Sea Ice is Our Highway - An Inuit Perspective on Transportation in the Arctic. A Contribution to the Arctic Marine Shipping Assessment. Inuit Circumpolar Council, Canada.
  11. ICC (2009) Circumpolar Inuit Health Summit. Yellowknife, Canada. Accessed on 2014-11-25 http://www.inuitcircumpolar.com/uploads/3/0/5/4/30542564/2009_healthsummitreport_final.pdf
  12. IPCC (2007) 4th assessment report, Climate change 2007: synthesis report. Accessed on 2014-11-20 http://www.ipcc.ch/pdf/assessment-report/ar4/syr/ar4_syr.pdf
  13. IPCC (2014) 5th assessment report 2013: AR5 Synthesis report. http://www.ipcc.ch/pdf/assessment-report/ar5/syr/SYR_AR5_LONGERREPORT.pdf
  14. Kral, M. (2003) Unikkaartuit: meanings of well-being, sadness, suicide, and change in two Inuit communities. Final Report to the National Health Research and Development Programs. Health Canada, Ottawa.
  15. Laidler et al (2009) Travelling and hunting in a changing Arctic: assessing Inuit vulnerability to sea ice change in Igloolik, Nunavut. Climatic Change 94:363–397 DOI 10.1007/s10584-008-9512-z
  16. Nuttall, M. Berkes, F. Forbes, B.C. Kofinas, G. Vlassova, T. & Wenzel, G. (2005) Hunting, Herding, Fishing, and Gathering: Indigenous Peoples and Renewable Resource Use in the Arctic. Pp. 649-690 in: Arctic Climate Impact Assessment. Cambridge, Cambridge University Press.
  17. Sørensen, M. (2010) Inuit landscape use and responses to climate change in the Wollaston Forland—Clavering Ø region, Northeast Greenland. Geografisk Tidsskrift-Danish Journal of Geography 110:155–174.
  18. Takano, T. (2004) Connections with the land: land skills courses in Igloolik, Nunavut. Ethnography 6:463–486.
  19. UNESCO (2009) Climate Change and Arctic Sustainable Development: scientific, social, cultural and educational challenges. UNESCO: Paris, 376 pp.
  20. Willox, A. et al (2013) The land enriches the soul: On climatic and environmental change, affect, and emotional health and well-being in Rigolet, Nunatsiavut, Canada. Emotion, Space and Society 6, 14-24.

Citation

Tove Björklund, Cláudia Florêncio, Rawaf al Rawaf, Tove Björklund, Rawaf al Rawaf , Juan Carlos Rocha. Arctic mobility. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-02-07 11:30:32 GMT.
Tuesday, 19 May 2015 19:51

Potential Salmon Collapse

Written by Linnéa Joandi

Potential Salmon Collapse

Main Contributors:

Daniele Crimella, Linnéa Joandi, Hanna Kylin, Kavita Oehme, Hanna Kylin

Other Contributors:

Reinette (Oonsie) Biggs, Jennifer Griffiths, Garry Peterson, Juan Carlos Rocha, Jennifer Griffiths

Summary

The potential regime shift in Alaska occurs in the marine system of the North Pacific Ocean. The present regime is characterised by a high abundance of salmon while a potential regime would be characterised by a low abundance of salmon. This is a speculative shift that has not yet occurred. The key feedbacks that maintains the current regime is the reinforcing loop of salmon population dynamics. Feedback mechanism are also present between the local communities´ needs, fishery regulation, salmon population and hatcheries´ effect. The key drivers that could cause the regime shift include climatic anomalies and extremes, fishing pressure, reduced population heterogeneity, variations in primary production, demand for food, the use of hatcheries, global warming, and changes in salmon population structure. Some possible leverage points for intervention to prevent this regime shift involves management concerned with fisheries, hatcheries and global warming.

Type of regime shift

  • Potential salmon fishery collapse

Ecosystem type

  • Marine & coastal

Land uses

  • Fisheries

Spatial scale of the case study

  • Sub-continental/regional (e.g. southern Africa, Amazon basin)

Continent or Ocean

  • North America
  • Pacific Ocean

Region

  • Alaska, North East Pacific Ocean

Countries

  • United States

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

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Citation

Daniele Crimella, Linnéa Joandi, Hanna Kylin, Kavita Oehme, Hanna Kylin, Reinette (Oonsie) Biggs, Jennifer Griffiths, Garry Peterson, Juan Carlos Rocha, Jennifer Griffiths. Potential Salmon Collapse. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-02-07 12:43:18 GMT.
Saturday, 25 January 2014 17:29

Tokaj wine region socialization

Written by Béla Kuslits

Tokaj wine region socialization

Main Contributors:

Béla Kuslits

Other Contributors:

Reinette (Oonsie) Biggs, Juan Carlos Rocha

Summary

Tokaj-Hegyalja, a wine region in north-eastern Hungary has undergone a regime shift from small-scale and high-quality wine producing strategy to a low-quality industrialized strategy. For centuries before the regime shift, mostly local families and wealthy individuals owned and operated the vineyards. The high-quality regime was maintained by the high number of wineries, the high level of local ecological knowledge and the access to the European markets where the wines were sold for good prices. After the Second World War Hungary remained under the Soviet influence, and a socialist, authoritarian regime started to govern the country. The vineyards and wineries in the Tokaj region were socialized and became parts of a large, state-operated winemaking company following a highly quantity-oriented strategy in wine-production and selling the wines in the socialist (Comcon) countries. First, the industrialized regime was forced by an external power, but later, the regime became stable as the number of wineries decreased, the local knowledge wasn't used any more and the vineyards were transformed to produce large quantities. Many high-quality but low productivity vineyards have been abandoned and became high biodiversity areas (mostly forests). Even after the political changes in 1989 the stable state remained intact as the most important factors sustaining the high-quality regime were lacking. This regime is maintained by a high demand for cheap wine, state subsidies and the missing contacts to the quality sensitive markets. Today, as the former Soviet market collapsed, the region is facing a poverty trap. As Hungary joined the European Union in 2004, the abandoned vineyards became Natura 2000 conservation areas, thus it is difficult to use them for agriculture. However, after the political changes in 1989 the state owned vineyards were privatized and there are more and more private wineries producing high-quality wines. Some of them have gained access to quality sensitive markets and started to operate in a new quality-oriented regime. It's however uncertain whether the region will flip back in the near future to a quality-oriented scheme or if it will remain a marginal strategy.

Type of regime shift

  • Governance change

Ecosystem type

  • Agro-ecosystems

Land uses

  • Small-scale subsistence crop cultivation
  • Large-scale commercial crop cultivation
  • Conservation

Spatial scale of the case study

  • Local/landscape (e.g. lake, catchment, community)

Continent or Ocean

  • Europe

Region

  • North-eastern Hungary, Tokaj-Hegyalja World Heritage Region

Countries

  • Hungary

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. EEA. (2013). Natura 2000 data - the European network of protected sites. 03.09.2013. Retrieved from http://www.eea.europa.eu/data-and-maps/data/natura-4
  2. Hegedűs, S. (1908). Kimutatás a Tokaji borvidékhez tartozó községek szőlőterületéről és borterméséről az 1900-1907 években. In Királyok Boráról Borok Királyáról Tokaji Nektárról Folyékony Aranyról. Tokaj: Frankel Dezső Villanyerőre Berendezett Könyvnyomdája.
  3. ICOMOS. (2002). Tokaji Wine Region (Hungary).
  4. Nyizsalovszki, R., & Virók, V. (2001). Területhasználat időbeli változásai és következményei egy tokaj-hegyaljai településen. In Földrajzi Konferencia. Szeged.
  5. UNESCO. (2002). Decisions Adopted by the 26th Session of the World Heritage Committee.

Citation

Béla Kuslits, Reinette (Oonsie) Biggs, Juan Carlos Rocha. Tokaj wine region socialization. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-02-07 12:46:05 GMT.
Thursday, 17 October 2013 17:42

Zululand Wetlands

Written by Linda Luvuno

Zululand Wetlands

Main Contributors:

Linda Luvuno, Linda Luvuno

Other Contributors:

Reinette (Oonsie) Biggs, Donovan Kotze, Damian Walters

Summary

The shift from herbaceous (grass and sedge dominated) wetlands to swamp forest occurs when wetlands predominately covered in herbaceous vegetation become invaded by woody plant species and irreversibly change to a forest state. This shift occurs when wetlands experience disturbances that affect their hydrology and their natural disturbance regimes, notably their fire regime. In this case study in Zululand, large scale afforestation in the landscape surrounding the wetlands has changed the catchment from a system that uses a low amount of water to a system that uses large amounts of water (through different transpiration rates). This drying has led to shorter periods of soil saturation, which has altered the hydrology of the wetlands. Together with fire suppression, this has caused a shift in regime from herbaceous wetlands to wetlands dominated by indigenous swamp forest species. This regime shift has impacted biodiversity as the wetlands support a rich biodiversity of herbaceous species including the only known wild population of the critically endangered Kniphofia leucocephala. These wetlands are within one of the key water source areas of South Africa, thus this change has affected water supply. Local communities use these wetlands for grazing cattle, and this shift has reduced the area available for grazing. Removing trees from the wetlands is often difficult, therefore managerial recommendations focus on the avoidance through the establishment of a frequent fire regime (biennial) to prevent the recruitment of young trees.  

Type of regime shift

  • Herbaceous wetland to Swamp Forest

Ecosystem type

  • Grasslands

Land uses

  • Extensive livestock production (natural rangelands)
  • Timber production
  • Conservation

Spatial scale of the case study

  • Local/landscape (e.g. lake, catchment, community)

Continent or Ocean

  • Africa

Region

  • KwaZulu-Natal

Countries

  • South Africa

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. Adie H, Richert S, Kiriman KP & Lawes MJ. 2011. The heat is on: frequent high intensity fire in bracken (Pteridium aquilinum) drives mortality of the sproutingrntree Protea caffra in temperate grasslands. Plant Ecology 212, 2013-2022.rn
  2. Clulow AD, Everson CS, Jarmain C & Mengistu M. 2012. Water-Use of the Dominant Natural Vegetation Types of the Eastern Shores Area, Maputaland. WRC Report No. 1926/1/12. Water Research Commission, Pretoria.
  3. Helmschrot J. 2005. Assessment of temporal and spatial effects of land use changes on wetland hydrology: A case study from South Africa. Wetlands: Monitoring, Modelling and Management. Taylor & Francis, London.
  4. Henkel JS, Ballenden C & Bayer A.W. 1936. An Account of the Plant Ecology of the Dukuduku Forest Reserve and Adjoining Areas of the Zululand Coastal belt. Annals of the Natal Museum 8(1), 95-125.
  5. Kirkman K, Goebel PC, West L, Drew MB & Palik BJ. 2000. Depressional wetland vegetation types: a question of plant Community development. Wetlands 20(2), 373-385.
  6. Kirkman LK. 1995. Impacts of fire and hydrological regimes on vegetation in Depression wetlands of Southeastern USA. In: Fire in wetlands: a management perspective. Proceedings of the Tall Timbers Fire Ecology Conference, No. 19. Tall Timbers Research Station, Tallahassee, Florida.
  7. Le Maitre DC, Scott DF & Colvin, C. 1999. A review of information on interactions between vegetation and groundwater. Water SA 25(2), 137-151.

Citation

Linda Luvuno, Linda Luvuno, Reinette (Oonsie) Biggs, Donovan Kotze, Damian Walters. Zululand Wetlands. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2013-10-24 14:41:30 GMT.
Thursday, 16 May 2013 10:17

Northern Benguela Marine System

Written by Catarina Larsson

Northern Benguela Marine System

Main Contributors:

Sophie Belton, Carolina Holmberg, Catarina Larsson, Shauna Mahajan

Other Contributors:

Juan-Paul Roux, Juan Carlos Rocha

Summary

This case study examines one of the regime shifts that took place in the Northern Benguela system; occurring in the 1990s from a high to low fish biomass state. This shift has been attributed to consistent overfishing, and was enhanced by large-scale environmental anomalies that occurred in the 1990s. Multiple drivers and feedbacks keep the system locked in the low biomass state. Jellyfish have exponentially grown in numbers, occupying the niche left by pelagic fish and suppressing regrowth in many stocks. Warmer sea temperatures decrease the ability for fish to spawn, keeping fish biomass low. Low fish biomass coupled with hypoxic events leads to phytoplankton blooms and reinforces the frequency and spatial scale of severe hypoxic conditions. The new, low biomass state has negatively impacted provisioning services from marine resources, regulating services maintaining marine water quality, and recreational fishing services. The loss in ecosystem services has both directly and indirectly impacted the well-being of multiple resource users within the system. Management of the system is now moving from a single-species approach towards an ecosystem-based management approach that takes into account trophic interactions as well as environmental variations affecting the system. This means, for example, setting catch limits for fisheries based on more than just fish biomass.

Type of regime shift

  • Marine food webs

Ecosystem type

  • Marine & coastal

Land uses

  • Fisheries

Spatial scale of the case study

  • Sub-continental/regional (e.g. southern Africa, Amazon basin)

Continent or Ocean

  • Africa
  • Atlantic Ocean

Region

  • Coast off south West African continent

Countries

  • Namibia

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. Bakun, A., Field, D.B., Redondo-Rodriguez, A. and Weeks, S.J. 2010. Greenhouse gas, upwelling-favorable winds, and the future of coastal ocean upwelling ecosystems.rnGlobal change biology. 16: 1213-1228. rn
  2. Berkes, F., Hughes, T.P., Steneck, R.S., Wilson, J.A., Bellwood, D.R., Crona, B., Folke, C., Gunderson, L.H., Leslie, H.M., Norberg, J., Nystru00f6m, M., Olsson, P., u00d6sterblom, H., Scheffer, M., Worm, B. 2006. Globalization, Roving Bandits, and Marine Resources. Science. 311 (5767): 1557-1558.
  3. Blamey, L. K., Howard, J. A. E., Agenbag, J. & Jarre, A. Regime-shifts in the southern Benguela shelf and inshore region. Progress in Oceanography 106, 80u201395 (2012).
  4. Boyer, D.C. and Hampton, I. 2001. An overview of the living marine resources of Namibia. South African Journal of Marine Science. 23:1, 5-35. rn
  5. Boyer, D.C., Boyer, H.J., Fossen, I. and Kreiner, A. 2001. Changes in abundance of the northern Benguela sardine stock during the decade 1990u20132000, with comments on the relative importance of fishing and the environment. South African Journal of Marine Science. 23(1): 67-84.
  6. Brierley, A.S., Axelsen, B.E., Buecher, E., Sparks, C.A.J., Boyer, H., Gibbons, M.J. 2001. Acoustic observations of jellyfish in the Namibian Benguela. Marine Ecology Progress Series, 210: 55u201366.
  7. Brotz, L., Cheung, W. W. L., Kleisner, K., Pakhomov, E. & Pauly, D. Increasing jellyfish populations: trends in Large Marine Ecosystems. Hydrobiologia (2012).doi:10.1007/s10750-012-1039-7.
  8. Bydu00e9n, S., Larsson, A-M. and Olsson, M .2003. Mu00e4ta vatten u2013 undersu00f6kningar av su00f6tt och salt vatten. Avdelning fu00f6r tillu00e4mpad milju00f6vetenskap och Avdelningen fu00f6r oceanografi, Gu00f6teborgs universitet, Bohuslu00e4n.
  9. Crawford, R.J.M., Shannon, L.V. and Pollock, D.E.1987. The Benguela ecosystem. IV: The major fish and invertebrate resources. Oceanography and marine biology. 25:353u2013505.
  10. Cury, P. and Shannon, L. 2004. Regime shifts in upwelling ecosystems: observed changes and possible mechanisms in the northern and southern Benguela. Progress in Oceanography. 60:223-243.
  11. de Young, B., Harris, R., Alheit, J., Beaugrand, G., Mantua, N. and Shannon, L. 2004. Detecting regime shifts in the ocean: data considerations. Progress in Oceanography. 60:143-164.
  12. Food and Agricultural Organization (FAO).1996. Precautionary approach to capture fisheries and species introductions. Technical guidelines for responsible fisheries. No. 2.
  13. Food and Agricultural Organization (FAO): Information on fisheries management in the republic of Namibia. 2001.
  14. Heymans, J.J., Shannon, L.J. and Jarre, A. 2004. Changes in the northern Benguela ecosystem over three decades: 1970s, 1980s, and 1990s. Ecological Modelling.172:175-195.
  15. Heymans, J.J., Shannon, L.J. and Jarre, A., 2004. The northern Benguela ecosystem: changes over three decades 1970s, 1980s and 1990s. Ecol. Model. 172: 175-195.
  16. Hofmann, E.E., and Powell, T.M. 1998. Environmental variability effects on marine fisheries: four case histories. Ecological Applications. 8: 23-32.
  17. Hutchings, L., van der Lingen, C.D., Shannon, L.J., Crawford, R.J.M., Verheye, H.M.S.,rnBartholomae, C.H., van der Plas, A.K., Louw D., Kreiner A., Ostrowski M., Fidel Q., Barlow R.G., Lamont T., Coetzee, J., Shillington, F., Veitch, J., Currie, J.C., and Monteiro, P.M.S., 2009. The Benguela Current: An ecosystem of four components. Progress in Oceanography. 83:15-32. rn
  18. Kreiner, A., Yemane, D., Stenevik, E.K. and Moroff, N.E. 2011. The selection of spawning location of sardine (Sardinops sagax) in the northern Benguela after changes in stock structure and environmental conditions. Fisheries oceanography. 20(6): 560-569. rn
  19. Lynam, C.P., Gibbons, M.J., Axelsen, B.E., Sparks, C.A.J., Coetzee, J., Heywood, B.G and Brierley, A.S. 2006. Jellyfish overtake fish in a heavily fished ecosystem. Current Biology. 16(13).
  20. Monteiro, P.M.S and van der Plas, A.K. 2006. Low oxygen water (LOW) variability in the Benguela system: Key processes and forcasting relevant to forecasting. Benguela Predicting a Large Marine Ecosystem, Large Marine Ecosystems. 14:71-90.
  21. Pascoe, S and Gru00e9boval. D. 2003. Measuring capacity in fisheries. FAO Fisheries Technical Paper. No. 445.
  22. Pu00f6rtner, H.O. and Langenbuch, M. 2005. Synergistic effects of temperature extremes, hypoxia, and increases in CO2 on marine animals: From Earth history to global change. Journal of Geophysical research. 110:C9.
  23. Richardson, A. J., Bakun, A., Graeme, C., Hays G.C., and Gibbons, M.J. 2009. The jellyfish joyride: causes, consequences and management responses to a more gelatinous future. Trends in Ecology & Evolution, 24(6): 312-322.rn
  24. Richardson, A.J., Bakun, A., Hays, G.C. and Gibbons, M. J. 2009. The jellyfish joyride: causes, consequences and management responses to a more gelatinous future. Trends in Ecology and Evolution 24(6),312-322.
  25. Roux, J-P and Shannon, L.J. 2004. Ecosystem approach to fisheries management in the northern Benguela: the Namibian experience. African Journal of Marine Science. 26(1): 79-93. rn
  26. Roux, J-P., van der Lingen, C., Gibbons, M.J., Moroff, N.E., Shannon, L.J., Smith, A.D.M. and Cury, P.M. 2013. Jellyfication of the marine ecosystems as a likely consequence of overfishing small pelagic fish: Lessons from the Benguela. Bulletin of Marine Science. 89(1):249u2013284.
  27. Sowman, M. and Cardoso, P. 2010. Small-scale fisheries and food security strategies in countries in the Benguela Current Large Marine Ecosystem (BCLME) region: Angola, Namibia and South Africa. Marine Policy. 34:1163u20131170.

Citation

Sophie Belton, Carolina Holmberg, Catarina Larsson, Shauna Mahajan, Juan-Paul Roux, Juan Carlos Rocha. Northern Benguela Marine System. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2013-08-26 08:47:14 GMT.
Tuesday, 27 November 2012 15:16

Chesapeake Bay

Written by Reinette (Oonsie) Biggs

Chesapeake Bay

Main Contributors:

Reinette (Oonsie) Biggs

Other Contributors:

Summary

The Chesapeake Bay is the largest estuary in the United States, and lies off the Atlantic Ocean, surrounded by Maryland and Virginia. The bay is mostly known for its seafood production, especially blue crabs, clams and oysters. In the middle of the twentieth century, the bay supported 9,000 full-time watermen, according to one account. Today, the body of water is less productive than it used to be because of runoff from urban areas (mostly on the Western Shore) and farms (especially on the Eastern Shore and in the Susquehanna River watershed), over-harvesting, and invasion of foreign species. In contrast to harvesting wild oysters, oyster farming is a growing industry for the bay to help maintain the estuary's productivity as well as a natural effort for filtering impurities from the water in an effort to reduce the effects of man-made pollution. 

Type of regime shift

Ecosystem type

  • Marine & coastal

Land uses

  • Urban
  • Large-scale commercial crop cultivation
  • Tourism

Spatial scale of the case study

  • Local/landscape (e.g. lake, catchment, community)

Continent or Ocean

  • North America

Region

  • East Coast

Countries

  • United States

Locate with Google Map

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. Boesch, D.F. 2004. Scientific requirements for ecosystem-based management in the restoration of Chesapeake Bay and Coastal Louisiana. Ecological Engineering. 26 (1) pp 6-26

Citation

Reinette (Oonsie) Biggs. Chesapeake Bay. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2012-11-27 15:27:41 GMT.
Monday, 12 November 2012 12:18

Black Sea: Gelatinous Plankton Dominance

Written by Laia d'Armengol

Black Sea: Gelatinous Plankton Dominance

Main Contributors:

Laia d'Armengol, Pau Torrents, Flor Luna, Grazzia Matamoros

Other Contributors:

Reinette (Oonsie) Biggs, Juan Carlos Rocha

Summary

The Black Sea is a marine and coastal system previously dominated by top predators. Overfishing and increased nutrient input during the last 50 years, as well as climate change, triggered a shift of the system into a gelatinous plankton dominated regime in the late 80's, after which a population outburst of the invasive jellyfish Mnemiopsis leidyi occurred. The main feedback maintaining the regime is M. leidyi feeding on pelagic larvae and being better a competitor for zooplankton than the native jellyfish Aurelia aurita and pelagic fish. Ecosystem services related with food provision, biodiversity, aesthetic and recreational values, and nutrient cycling were affected by the regime shift. Management actions to restore the top predator regime include enforcement of fishing regulations, regional policies aimed to reduce excess nutrient input and the biological control of M. leidyi.  

Type of regime shift

  • Invasive Species Dominance

Ecosystem type

  • Marine & coastal

Land uses

  • Urban
  • Small-scale subsistence crop cultivation
  • Large-scale commercial crop cultivation
  • Fisheries
  • Tourism

Spatial scale of the case study

  • Sub-continental/regional (e.g. southern Africa, Amazon basin)

Continent or Ocean

  • Asia
  • Europe

Region

  • Eastern Europe and Asia Minor

Countries

  • Austria
  • Romania

Locate with Google Map

Drivers

Key direct drivers

  • Vegetation conversion and habitat fragmentation
  • Infrastructure development

Land use

  • Extensive livestock production (rangelands)

Impacts

Ecosystem type

  • Grasslands
  • Tundra
  • Polar
  • Agro-ecosystems

Key Ecosystem Processes

  • Soil formation
  • Primary production
  • Nutrient cycling
  • Water cycling

Biodiversity

  • Biodiversity

Provisioning services

  • Livestock
  • Wild animal and plant products
  • Woodfuel

Regulating services

  • Climate regulation
  • Regulation of soil erosion

Cultural services

  • Recreation
  • Aesthetic values
  • Knowledge and educational values
  • Spiritual and religious

Human Well-being

  • Food and nutrition
  • Livelihoods and economic activity
  • Cultural, aesthetic and recreational values
  • Social conflict
  • Cultural identity

Key Attributes

Spatial scale of RS

  • Local/landscape

Time scale of RS

  • Decades
  • Centuries

Reversibility

  • Readily reversible

Evidence

  • Contemporary observations
  • Experiments

Confidence: Existence of RS

  • Well established – Wide agreement in the literature that the RS exists

Confidence: Mechanism underlying RS

  • Well established – Wide agreement on the underlying mechanism

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Alternate regimes

The Yamal Peninsula consists entirely of low Arctic tundra and contains a variety of lichen, moss, graminoid, and shrub species.  Although vegetation shifts can be described in other low tundra areas, the Yamal peninsula is unique due to the delayed exploitation of hydrocarbons as a result of the Soviet Union collapse (Kumpula et al. 2012).  The Yamal Peninsula nomadic Nenets and reindeer, the largest reindeer-herder society in the world (Zeng et al. 2013), both rely on this landscape for their livelihood while simultaneously shaping the state of the landscape (Walker et al. 2009).  This report views the Yamal Peninsula and Nenets society as a social-ecological system; however, emphasis is placed on changes in the ecosystem. 

Open land with reindeer herding

In this regime the landscape consists of lichen, moss, and graminoid species. The density of reindeer and intensity of grazing determines whether lichen, moss, or graminoid species dominate the landscape (van der Wal 2005). Small deciduous shrubs can also be found in this regime; however, they will only be found in small patches. A key feature of this regime is that it is an open landscape and allows the Nenets and their reindeer herds to roam across the land.  The vegetation existing in this regime is palatable for reindeers, and thus, reindeer grazing largely maintains this open landscape (Yu et al. 2011; Walker et al. 2009). 

 

Shrubland without reindeer herding

This regime is dominated by deciduous and evergreen shrubs.  A defining feature of this regime is that the shrubs are densely packed on the landscape, making it difficult for reindeer and Nenets to roam across the land.  Dense shrubland has the potential to form near areas where gas infrastructure has been built (Forbes et al. 2009), making it difficult for Nenets and their reindeer herds to reach this land.  Alternatively, dense shrubland can also form due to overgrazing from a high density of reindeer (Yu et al. 2011).  Reinforcing feedback mechanism allows for shrub encroachment to expand (Myers-Smith 2005). Rising temperatures and longer summers as a result of climate change are having large effects on vegetation, with thawing permafrost, landslides, and shrub encroachment (Forbes et al. 2009, Kumpala et al. 2012).

Drivers and causes of the regime shift

Shift from open land with reindeer herding to shrubland without reindeer herding

Currently, the dominant vegetation in low Arctic tundra is composed of mosses, lichens and graminoids. However, it has been observed a transition from these growth forms to shrubs during the last three decades in Eurasia (Kullman 2002; Aune et al. 2011; Yu et al. 2011; Macias-Fauria et al. 2012) and five decades in North America (Sturm et al. 2005Tape et al. 2006; Myers-Smith 2007). Temperature is considered a key factor in controlling vegetation growth in this ecosystem (Grace et al. 2002; Zeng et al. 2013).

The main driver of this regime shift is the rate of warming; -1 to 2oC during the last five decades in the tundra (Aune et al. 2011). The temperature rise has caused mild winters (Sturm et al. 2005), warmer summers (Kullman 2002; Macias-Fauria et al. 2012), and longer growing seasons (Zeng et al. 2013).

The temperature rise in the tundra has changed controlling feedbacks such as vegetation growth rates, microbial activity, and nutrient cycling  (Myers-Smith 2007; Yu et al. 2011). The new conditions have benefited the establishment, survival and growth of seedlings and saplings, which are the most vulnerable reproduction phases of trees and shrubs in this ecosystem (Kullman 2002). These changes in the current tundra regime lead to shrub encroachment, which in turn decreases the presence of mosses, grasses, and lichens by shading them.

 

Shift from Shrubland without reindeer herding to open land with reindeer herding

Shrub encroachment in the Arctic Tundra caused by temperature rise is controlled by large herbivore grazing (Olofsson et al. 2009). Yu et al. (2011) found that reindeers in Yamal peninsula graze mosses, lichens, deciduous shrubs and grasses, except evergreen shrubs because of its low nitrogen concentration and poor digestibility. However, reindeer trampling could decline the evergreen shrubs because they have the slowest growth rate in the tundra vegetation (Yu et al. 2011), which make its recovery  from this type of disturbance difficult. Heavy grazing could lead to a shift from shrub dominated tundra to moss graminoid-dominated tundra because the latter have faster growth rates than shrubs (Yu et al. 2011).

 

How the regime shift worked

Shift from open land with reindeer herding to shrubland without reindeer herding

Open land with reindeer herding regime is largely maintained by the reindeer grazing and trampling activities (Yu et al. 2011; van der Wal 2005).  Maintaining open land with a reindeer herding regime is largely dependent on the density and abundance of reindeer on the Yamal Peninsula.  If there were a sudden decline in the reindeer population, the grazing/trampling-nutrient restoring reinforcing feedback loop would no longer be strong enough to maintain an open land regime (Yu et al. 2011).  Alternatively, as grazing intensity reaches overgrazing, shrubs start to dominate the landscape (Bråthen et al 2007; Yu et al. 2011).  Thus, if the density of reindeer exceed the land’s carrying capacity, it can also lead to a shift to a shrub-dominated regime. Indirectly, the Nenets impact the open land regime; the number of reindeer herding Nenets loosely determines how many reindeer will be able to use the land (Kumpala et al. 2012).  A main driver of change impacting Nenets-reindeer relations comes from gas exploitation on the Yamal Peninsula.  An increase in gas exploitation infrastructure (ex. pipelines, etc.) has the potential to fragment the land (Forbes et al. 2009), and therefore disrupt the reindeer driven reinforcing feedback loop.

Once the land enters a shrub-dominated regime without reindeer herding, a reinforcing feedback loop promotes the establishment of more shrubs (Myers-Smith 2007). In addition, there is an established link between Arctic warming and an increase in deciduous shrub biomass (Macias-Fauria et al. 2012), which further interacts with the establishment of a self-reinforcing shrub-dominated regime.  

 

Shift from shrubland without reindeer herding to open land with reindeer herding

To shift from a shrubland to open land would require shrubs to be removed from the field. This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).  Although this would initially cause a shift to more open land, one could speculate that this would fragment the land, contributing to a shift back to shrubland.  A more persistent force to shift the land from shrubland to open land would come from the reindeer.  Although it is difficult for reindeer to move through dense shrubland, and only some shrubs are part of reindeer diet, reindeer help convert shrub land to open land through grazing and trampling (Yu et al. 2011).

 

Impacts on ecosystem services and human well-being

Shrubs to grass:

When shrubland shifts to open land, biodiversity and connectivity go down, with fewer habitats for birds (Henden et al. 2013). In the long run, a shift towards open land could diminish biodiversity as an ecosystem service for the Yamal-Nenets, possibly leading to a degraded landscape and loss of productive reindeer herding land (Bråthen et al. 2007). The reindeers graze on dwarf shrubs, like willows. When shrubs are replaced by grass, Nenets lose provisional ecosystem services, such as food sources for the reindeers, and more importantly stocks of firewood (Walker et al. 2009, Degteva & Nellemann 2013). Gains from the shift for the Nenets are the graminoid-dominated pastures, which lead to an increase in provisioning ecosystem services. In Yamal the loss of shrubs has been compensated for by the net increases in productivity among highly nutritious and digestible forage species (Forbes et al. 2009). This has given way for more reindeers, which means more resources to be able to access provisional ecosystem services: food, clothing and antlers to trade with the gas company employees (Forbes et al. 2009, Kumpala et al. 2012, Forbes et al. 2013, Degteva & Nellemann 2013). As for regulating services, increased abundance of reindeers leads to a reinforcing feedback, which keeps the grass state by trampling, grazing, and addition of nutrients (Forbes et al. 2009). 

Grassland has been suggested to dampen global warming, due to increased albedo in winter (Zimov et al. 1995). The graminoid landscape state could thus be beneficial for human wellbeing in Yamal, since it could dampen temperature and lead to less thawing of permafrost, and less problems such as landslides and erosion. Cultural ecosystem services increase in that nomadic life is based on herding, so aesthetic, spiritual and recreational services will increase from the shift. Nenets clearly benefit in the short run from this regime shift. No other groups of humans lose or gain anything substantial.

 

Shift from open land to shrubs:

If large patches, and eventually whole areas, of the tundra shift into the shrub state, reindeer herding would be hard to maintain since reindeer only graze shrubs up to a certain size, and with warmer climate shrub size will increase (Walker et al. 2011). Regulating services from reindeers, such as grazing and trampling, would decline. With this shift - especially if combined with the expected severe land use change due to Yamal gas exploitation (Kumpala et al. 2012) - provisional services for the Nenets would decrease due to the lower abundance of reindeers. This would in turn diminish a wide array of cultural and spiritual ecosystem services, such as lost sense of place, practices of the everyday life on the tundra, and holy places (Forbes et al. 2009, Kumpala et al. 2012).

Increased shrubland would, on the other hand, be beneficial for biodiversity, opening up for larger populations of birds (Henden et al. 2013), herbivores other than reindeers, and predators such as wolves and wolverines (Golovatin et al. 2012). With this succession, in combination of the expected influx of thousands of migrant oil and gas workers, there could be increased possibilities for hunting and recreation.

 

Management options

The shrub dominated regime is seen as an undesirable regime since the vegetation is unfavorable for the Nenets nomads’ traditional reindeer herding lifestyle. If there would be an aim of keeping the landscape in a shrub dominated state there cannot be any reindeers or few reindeers in the area. The shrubs are growing at a slow pace which means that if there are no grazing animals disturbing this growth process there will be a maintained regime of mature shrubs (Bråthen et al. 2007). To shift from a shrubland to open land would require shrubs to be removed from the field.  This could be done through clearing shrubland to build roads or pipelines in relation to gas exploitation development on the Yamal Peninsula (Forbes et al. 2009).

 

Key References

  1. Daskalov, G, Grishin, A, Rodionov, S, & Mihneva, V. 2007. Trophic cascades triggered by overfishing reveal possible mechanisms of ecosystem regime shifts. Proceedings of the National Academy of Sciences 104 (25), 10518-10523.rnrn
  2. Graham WM, S Gelcich, K L Robinson, CM Duarte, L Brotz, JE Purcell, LP Madin, H Mianzan, KR Sutherland, S Uye, KA Pitt, CH Lucas, M Bøgeberg, RD Brodeur, RH Condon 2014. Linking human well-being and jellyfish: ecosystem services, impacts, and societal responses. Frontiers in Ecology and the Environment 12: 515–523. http://dx.doi.org/10.1890/130298
  3. Oguz, T & Gilbert, D. 2006. Abrupt transitions of the top-down controlled Black Sea pelagic ecosystem during 1960-2000: Evidence for regime shifts under strong fishery exploitation and nutrient enrichment modulated by climate-induced variations. Science Direct 54, 220-242.

Citation

Laia d'Armengol, Pau Torrents, Flor Luna, Grazzia Matamoros, Reinette (Oonsie) Biggs, Juan Carlos Rocha. Black Sea: Gelatinous Plankton Dominance. In: Regime Shifts Database, www.regimeshifts.org. Last revised 2017-02-07 12:05:45 GMT.
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