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Margareta Johansson

Researcher

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Long-term in situ permafrost thaw effects on bacterial communities and potential aerobic respiration

Author

  • Sylvain Monteux
  • James T. Weedon
  • Gesche Blume-Werry
  • Konstantin Gavazov
  • Vincent E.J. Jassey
  • Margareta Johansson
  • Frida Keuper
  • Carolina Olid
  • Ellen Dorrepaal

Summary, in English

The decomposition of large stocks of soil organic carbon in thawing permafrost might depend on more than climate change-induced temperature increases: indirect effects of thawing via altered bacterial community structure (BCS) or rooting patterns are largely unexplored. We used a 10-year in situ permafrost thaw experiment and aerobic incubations to investigate alterations in BCS and potential respiration at different depths, and the extent to which they are related with each other and with root density. Active layer and permafrost BCS strongly differed, and the BCS in formerly frozen soils (below the natural thawfront) converged under induced deep thaw to strongly resemble the active layer BCS, possibly as a result of colonization by overlying microorganisms. Overall, respiration rates decreased with depth and soils showed lower potential respiration when subjected to deeper thaw, which we attributed to gradual labile carbon pool depletion. Despite deeper rooting under induced deep thaw, root density measurements did not improve soil chemistry-based models of potential respiration. However, BCS explained an additional unique portion of variation in respiration, particularly when accounting for differences in organic matter content. Our results suggest that by measuring bacterial community composition, we can improve both our understanding and the modeling of the permafrost carbon feedback.

Department/s

  • Dept of Physical Geography and Ecosystem Science
  • MERGE: ModElling the Regional and Global Earth System
  • BECC: Biodiversity and Ecosystem services in a Changing Climate

Publishing year

2018-09

Language

English

Pages

2129-2141

Publication/Series

ISME Journal

Volume

12

Issue

9

Document type

Journal article

Publisher

Nature Publishing Group

Topic

  • Geosciences, Multidisciplinary

Status

Published

ISBN/ISSN/Other

  • ISSN: 1751-7362