The transition from stochastic to deterministic bacterial community assembly during permafrost thaw succession

Abstract

The Northern high latitudes are warming twice as fast as the global average, and
permafrost has become vulnerable to thaw. Changes to the environment during
thaw leads to shifts in microbial communities and their associated functions, such
as greenhouse gas emissions. Understanding the ecological processes that structure
the identity and abundance (i.e., assembly) of pre- and post-thaw communities may
improve predictions of the functional outcomes of permafrost thaw. We characterized
microbial community assembly during permafrost thaw using in situ observations
and a laboratory incubation of soils from the Storflaket Mire in Abisko, Sweden,
where permafrost thaw has occurred over the past decade. In situ observations
indicated that bacterial community assembly was driven by randomness (i.e., stochastic
processes) immediately after thaw with drift and dispersal limitation being the
dominant processes. As post-thaw succession progressed, environmentally driven
(i.e., deterministic) processes became increasingly important in structuring microbial
communities where homogenizing selection was the only process structuring upper
active layer soils. Furthermore, laboratory-induced thaw reflected assembly dynamics
immediately after thaw indicated by an increase in drift, but did not capture the longterm
effects of permafrost thaw on microbial community dynamics. Our results did
not reflect a link between assembly dynamics and carbon emissions, likely because
respiration is the product of many processes in microbial communities. Identification
of dominant microbial community assembly processes has the potential to improve
our understanding of the ecological impact of permafrost thaw and the permafrost–
climate feedback.

Keywords

permafrost thaw; microbial community; community assembly; phylogenetic null modeling; ecological processes

Published in

Frontiers in Microbiology
2020, Volume: 11, article number: 596589

SLU Authors

• Monteux, Sylvain

  • Department of Soil and Environment, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Ecology
Microbiology


Publication identifier

DOI: https://doi.org/10.3389/fmicb.2020.596589

Permanent link to this page (URI)

https://res.slu.se/id/publ/108965