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Carbon balance of Arctic tundra under increased snow cover mediated by a plant pathogen

Nature Climate Change volume 1, pages 220223 (2011) | Download Citation


Climate change is affecting plant community composition1 and ecosystem structure, with consequences for ecosystem processes such as carbon storage2,3,4. Climate can affect plants directly by altering growth rates1, and indirectly by affecting predators and herbivores, which in turn influence plants5,6,7,8,9. Diseases are also known to be important for the structure and function of food webs10,11,12,13,14. However, the role of plant diseases in modulating ecosystem responses to a changing climate is poorly understood15,16. This is partly because disease outbreaks are relatively rare and spatially variable, such that that their effects can only be captured in long-term experiments. Here we show that, although plant growth was favoured by the insulating effects of increased snow cover in experimental plots in Sweden, plant biomass decreased over the seven-year study. The decline in biomass was caused by an outbreak of a host-specific parasitic fungus, Arwidssonia empetri, which killed the majority of the shoots of the dominant plant species, Empetrum hermaphroditum, after six years of increased snow cover. After the outbreak of the disease, instantaneous measurements of gross photosynthesis and net ecosystem carbon exchange were significantly reduced at midday during the growing season. Our results show that plant diseases can alter and even reverse the effects of a changing climate on tundra carbon balance by altering plant composition.

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The Abisko Scientific Research Station provided accommodation, laboratory facilities and funding during the periods of field work. The study was supported by grants from the Centre for Environmental Research in Umeå  (CMF) and The Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning to J.O. and NER/A/S/2001/00460 from the Natural Environment Research Council, UK, to R.B.

Author information


  1. Department of Ecology and Environmental Science, Umeå University, SE-901 87 Umeå, Sweden

    • Johan Olofsson
    • , Lars Ericson
    •  & Mikaela Torp
  2. Department of Ecology, Swedish University of Agricultural Sciences, Box 7044, SE-750 07 Uppsala, Sweden

    • Mikaela Torp
  3. Finnish Forest Research Institute, Rovaniemi Research Station, FIN-96301 Rovaniemi, Finland

    • Sari Stark
  4. School of Biological and Biomedical Sciences, Centre for Ecosystem Science, University of Durham, Durham DH1 3LE, UK

    • Robert Baxter


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R.B. initiated the field experiment and managed it together with J.O. S.S. carried out the soil analyses. R.B. and J.O. were together responsible for all other field measurements. M.T. contributed to the field work. J.O., L.E. and R.B. outlined the scope of the study and linked various components. J.O. carried out the statistical analyses and wrote the manuscript, to which all authors contributed with discussions and text.

Competing interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to Johan Olofsson.

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