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

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

*Corresponding author for this work

    Research output: Contribution to JournalArticleAcademicpeer-review

    Abstract

    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.

    Original languageEnglish
    Pages (from-to)2129-2141
    Number of pages13
    JournalISME Journal
    Volume12
    Issue number9
    Early online date6 Jun 2018
    DOIs
    Publication statusPublished - Sept 2018

    Funding

    Acknowledgements We thank Tuukka Mäkiranta, Pia Bartels, and the Arctic Ecosystems students (2015) for help during field work; and the Abisko Scientific Research Station for practical support. Funding: This study was funded by a Wallenberg Academy Fellowship (KAW 2012.0152), Swedish Research Council (Dnr 621-2011-5444), and Formas (Dnr 214-2011-788) grants all attributed to ED. JTW was supported by a postdoctoral fellowship from the Flemish Science Foundation (FWO).

    FundersFunder number
    Flemish Science Foundation
    Svenska Forskningsrådet FormasDnr 214-2011-788
    Fonds Wetenschappelijk Onderzoek
    Knut och Alice Wallenbergs StiftelseKAW 2012.0152
    VetenskapsrådetDnr 621-2011-5444

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