Long-term warming alters the composition of Arctic soil microbial communities

Authors

  • Julie R. Deslippe,

    Corresponding author
    1. Landcare Research New Zealand Ltd, Palmerston North, New Zealand
    • Department of Forest Science, Faculty of Forest Science, University of British Columbia, Vancouver, BC, Canada
    Search for more papers by this author
  • Martin Hartmann,

    1. Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
    2. Department of Soil Sciences, Swiss Federal Research Institute WSL, Birmensdorf, Switzerland
    3. Molecular Ecology, Agroscope Reckenholz-Tänikon Research Station ART, Zurich, Switzerland, and Soil Sciences, Birmensdorf, Switzerland
    Search for more papers by this author
  • Suzanne W. Simard,

    1. Department of Forest Science, Faculty of Forest Science, University of British Columbia, Vancouver, BC, Canada
    Search for more papers by this author
  • William W. Mohn

    1. Department of Microbiology and Immunology, Life Sciences Institute, University of British Columbia, Vancouver, BC, Canada
    Search for more papers by this author

Correspondence: Julie R. Deslippe, Landcare Research New Zealand Ltd, Riddet Road, Massey University Campus, Private Bag 11052, Palmerston North 4442, New Zealand. Tel.: +64 6 353 4929; fax: +64 6 353 4801; e-mail: deslippej@landcareresearch.co.nz

Abstract

Despite the importance of Arctic soils in the global carbon cycle, we know very little of the impacts of warming on the soil microbial communities that drive carbon and nutrient cycling in these ecosystems. Over a 2-year period, we monitored the structure of soil fungal and bacterial communities in organic and mineral soil horizons in plots warmed by greenhouses for 18 years and in control plots. We found that microbial communities were stable over time but strongly structured by warming. Warming led to significant reductions in the evenness of bacterial communities, while the evenness of fungal communities increased significantly. These patterns were strongest in the organic horizon, where temperature change was greatest and were associated with a significant increase in the dominance of the Actinobacteria and significant reductions in the Gemmatimonadaceae and the Proteobacteria. Greater evenness of the fungal community with warming was associated with significant increases in the ectomycorrhizal fungi, Russula spp., Cortinarius spp., and members of the Helotiales suggesting that increased growth of the shrub Betula nana was an important mechanism driving this change. The shifts in soil microbial community structure appear sufficient to account for warming-induced changes in nutrient cycling in Arctic tundra as climate warms.

Ancillary