Skip to main content

Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles and JavaScript.

Consequences of warming on tundra carbon balance determined by reindeer grazing history

Abstract

Arctic tundra currently stores half of the global soil carbon (C) stock1. Climate warming in the Arctic may lead to accelerated CO2 release through enhanced decomposition and turn Arctic ecosystems from a net C sink into a net C source, if warming enhances decomposition more than plant photosynthesis2. A large portion of the circumpolar Arctic is grazed by reindeer/caribou, and grazing causes important vegetation shifts in the long-term. Using a unique experimental set-up, where areas experiencing more than 50 years of either light (LG) or heavy (HG) grazing were warmed and/or fertilized, we show that under ambient conditions areas under LG were a 70% stronger C sink than HG areas. Although warming decreased the C sink by 38% under LG, it had no effect under HG. Grazing history will thus be an important determinant in the response of ecosystem C balance to climate warming, which at present is not taken into account in climate change models.

This is a preview of subscription content

Access options

Buy article

Get time limited or full article access on ReadCube.

$32.00

All prices are NET prices.

Figure 1: Midday (08:00–18:00) CO2-C flux rates averaged over growing seasons 2011–2012 in a subarctic tundra heath under light grazing (LG), short-term reindeer exclusion (HGexc) and heavy grazing (HG) by the reindeer.
Figure 2: The total abundance of vegetation and litter in a subarctic tundra heath under light grazing (LG), short-term reindeer exclusion (HGexc) and heavy grazing (HG) by the reindeer.
Figure 3: Seasonal patterns in Re in a subarctic tundra heath under light grazing (LG), short-term reindeer exclusion (HGexc) and heavy grazing (HG) by the reindeer.
Figure 4: Normalized difference vegetation index in a subarctic tundra heath under light grazing (LG), short-term reindeer exclusion (HGexc) and heavy grazing (HG) by the reindeer.

References

  1. Tarnocai, C. et al. Soil organic carbon pools in the northern circumpolar permafrost region. Glob. Biogeochem. Cycle 23, GB2023 (2009).

    Article  Google Scholar 

  2. Davidson, E. A. & Janssens, I. A. Temperature sensitivity of soil carbon decomposition and feedbacks to climate change. Nature 440, 165–173 (2006).

    CAS  Article  Google Scholar 

  3. Forbes, B. C. & Kumpula, T. The ecological role and geography of reindeer (Rangifer tarandus) in northern Eurasia. Geogr. Compass 3, 1356–1380 (2009).

    Article  Google Scholar 

  4. Stark, S., Strömmer, R. & Tuomi, J. Reindeer grazing and soil microbial processes in two suboceanic and two subcontinental tundra heaths. Oikos 97, 69–78 (2002).

    Article  Google Scholar 

  5. Olofsson, J., Stark, S. & Oksanen, L. Reindeer influence on ecosystem processes in the tundra. Oikos 105, 386–396 (2004).

    CAS  Article  Google Scholar 

  6. Post, E. & Pedersen, C. Opposing plant community responses to warming with and without herbivores. Proc. Natl Acad. Sci. USA 105, 12353–12358 (2008).

    CAS  Article  Google Scholar 

  7. Olofsson, J. et al. Herbivores inhibit climate-driven shrub expansion on the tundra. Glob. Change Biol. 15, 2681–2693 (2009).

    Article  Google Scholar 

  8. Cahoon, S. M., Sullivan, P. F., Post, E. & Welker, J. M. Large herbivores limit CO2 uptake and suppress carbon cycle responses to warming in West Greenland. Glob. Change Biol. 18, 469–479 (2012).

    Article  Google Scholar 

  9. Olofsson, J. Short-and long-term effects of changes in reindeer grazing pressure on tundra heath vegetation. J. Ecol. 94, 431–440 (2006).

    Article  Google Scholar 

  10. Myers-Smith, I.H. et al. Shrub expansion in tundra ecosystems: Dynamics, impacts and research priorities. Environ. Res. Lett. 6, 045509 (2011).

    Article  Google Scholar 

  11. Hobbie, S. E. Temperature and plant species control over litter decomposition in Alaskan tundra. Ecol. Monogr. 66, 503–522 (1996).

    Article  Google Scholar 

  12. Cahoon, S. M., Sullivan, P. F., Shaver, G. R., Welker, J. M. & Post, E. Interactions among shrub cover and the soil microclimate may determine future Arctic carbon budgets. Ecol. Lett. 15, 1415–1422 (2012).

    Article  Google Scholar 

  13. Euskirchen, E., Bret-Harte, M. S., Scott, G. J., Edgar, C. & Shaver, G. R. Seasonal patterns of carbon dioxide and water fluxes in three representative tundra ecosystems in northern Alaska. Ecosphere 3, 1–19 (2012).

    Article  Google Scholar 

  14. Sjögersten, S., van der Wal, R., Loonen, M. J. J. E. & Woodin, S. J. Recovery of ecosystem carbon fluxes and storage from herbivory. Biogeochemistry 106, 357–370 (2011).

    Article  Google Scholar 

  15. Olofsson, J. & Oksanen, L. Role of litter decomposition for the increased primary production in areas heavily grazed by reindeer: A litterbag experiment. Oikos 96, 507–515 (2002).

    Article  Google Scholar 

  16. Olofsson, J., Kitti, H., Rautiainen, P., Stark, S. & Oksanen, L. Effects of summer grazing by reindeer on composition of vegetation, productivity and nitrogen cycling. Ecography 24, 13–24 (2001).

    Article  Google Scholar 

  17. Volk, M. et al. Subalpine grassland carbon dioxide fluxes indicate substantial carbon losses under increased nitrogen deposition, but not at elevated ozone concentration. Glob. Change Biol. 17, 366–376 (2011).

    Article  Google Scholar 

  18. Christiansen, C. T., Svendsen, S. H., Schmidt, N. M. & Michelsen, A. High Arctic heath soil respiration and biogeochemical dynamics during summer and autumn freeze-in-effects of long-term enhanced water and nutrient supply. Glob. Change Biol. 18, 3224–3236 (2012).

    Article  Google Scholar 

  19. Hafner, S. et al. Effect of grazing on carbon stocks and assimilate partitioning in a Tibetan montane pasture revealed by 13CO2 pulse labeling. Glob. Change Biol. 18, 528–538 (2012).

    Article  Google Scholar 

  20. Eskelinen, A. Herbivore and neighbour effects on tundra plants depend on species identity, nutrient availability and local environmental conditions. J. Ecol. 96, 155–165 (2008).

    Google Scholar 

  21. Post, E. S. & Klein, D. R. Relationships between graminoid growth form and levels of grazing by caribou (Rangifer tarandus) in Alaska. Oecologia 107, 364–372 (1996).

    Article  Google Scholar 

  22. Ravolainen, V. T. et al. Rapid, landscape scale responses in riparian tundra vegetation to exclusion of small and large mammalian herbivores. Basic Appl. Ecol. 12, 643–653 (2011).

    Article  Google Scholar 

  23. Tommervik, H., Dunfjeld, S., Olsson, G. A. & Ostby Nilsen, M. Detection of ancient reindeer pens, cultural remains and anthropogenic influenced vegetation in Byrkije (Borgefjell) mountains, Fennoscandia. Landscape Urban Plan. 98, 56–71 (2010).

    Article  Google Scholar 

  24. Josefsson, T., Hörnberg, G. & Östlund, L. Long-term human impact and vegetation changes in a boreal forest reserve: Implications for the use of protected areas as ecological references. Ecosystems 12, 1017–1036 (2009).

    Article  Google Scholar 

  25. Räsänen, S., Froyd, C. & Goslar, T. The impact of tourism and reindeer herding on forest vegetation at Saariselkä, Finnish Lapland: A pollen analytical study of a high-resolution peat profile. Holocene 17, 447–456 (2007).

    Article  Google Scholar 

  26. Zamin, T. J. & Grogan, P. Caribou exclusion during a population low increases deciduous and evergreen shrub species biomass and nitrogen pools in low Arctic tundra. J. Ecol. 101, 671–683 (2013).

    CAS  Article  Google Scholar 

  27. Elmendorf, S., Henry, G. H. R., Hollister, R. D. & Björk, R. G. Global assessment of experimental climate warming on tundra vegetation: Heterogeneity over space and time. Ecol. Lett. 15, 164–175 (2012).

    Article  Google Scholar 

  28. Bokhorst, S. et al. Microclimate impacts of passive warming methods in Antarctica: Implications for climate change studies. Polar Biol. 34, 1421–1435 (2011).

    Article  Google Scholar 

  29. Phoenix, G. K. et al. Impacts of atmospheric nitrogen deposition: Responses of multiple plant and soil parameters across contrasting ecosystems in long-term field experiments. Glob. Change Biol. 18, 1197–1215 (2012).

    Article  Google Scholar 

  30. Mack, M. C., Schuur, E. A. G., Bret-Harte, M. S., Shaver, G. R. & Chapin, F. S. Ecosystem carbon storage in Arctic tundra reduced by long-term nutrient fertilization. Nature 43, 440–443 (2004).

    Article  Google Scholar 

Download references

Acknowledgements

We thank A. Niva and S. Aakkonen for their valuable help with the field experiments. We thank Su. Katves and Si. Katves for assisting with vegetation recording and J. Hyvönen for helping with the statistical analysis. This study was funded by the Academy of Finland (project numbers 218121 and 130507).

Author information

Authors and Affiliations

Authors

Contributions

S.St. and M.V. initiated and managed the field experiment. J.O. and S.Sj contributed to the planning of the experiment. M.V. and H.Y. carried out C flux measurements with contributions from S.St. and S.Sj. E.K. and J.O. were responsible for plant and NDVI analyses. N.C. was responsible for modelling C fluxes. M.V. carried out the statistical analyses. M.V. and S.St. wrote the manuscript, to which all other authors contributed with discussions and text.

Corresponding author

Correspondence to Maria Väisänen.

Ethics declarations

Competing interests

The authors declare no competing financial interests.

Supplementary information

Rights and permissions

Reprints and Permissions

About this article

Cite this article

Väisänen, M., Ylänne, H., Kaarlejärvi, E. et al. Consequences of warming on tundra carbon balance determined by reindeer grazing history. Nature Clim Change 4, 384–388 (2014). https://doi.org/10.1038/nclimate2147

Download citation

  • Received:

  • Accepted:

  • Published:

  • Issue Date:

  • DOI: https://doi.org/10.1038/nclimate2147

Further reading

Search

Quick links

Nature Briefing

Sign up for the Nature Briefing newsletter — what matters in science, free to your inbox daily.

Get the most important science stories of the day, free in your inbox. Sign up for Nature Briefing