Resilience in soil bacterial communities of the boreal forest from one to five years after wildfire across a severity gradient

Journal Article · Mon Jun 13 00:00:00 EDT 2022 · Soil Biology and Biochemistry

DOI:https://doi.org/10.1016/j.soilbio.2022.108755· OSTI ID:1977650

Whitman, Thea  ^[1]; Woolet, Jamie ^[2]; Sikora, Miranda  ^[1]; Johnson, Dana B.  ^[1]; Whitman, Ellen ^[3]

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1. Univ. of Wisconsin, Madison, WI (United States)
2. Univ. of Wisconsin, Madison, WI (United States); Colorado State Univ., Fort Collins, CO (United States)
3. Natural Resources Canada, Edmonton, AB (Canada)

Wildfires can represent a major disturbance to ecosystems, including soil microbial communities belowground. Furthermore, fire regimes are changing in many parts of the world, altering and often increasing fire severity, frequency, and size. The boreal forest and taiga plains ecoregions of northern Canada are characterized by naturally-occurring stand-replacing wildfires on a 40–350 year basis. We previously studied the effects of wildfire on soil microbial communities one year post-fire across 40 sites, spanning a range of burn severity. Here, we return to the same sites five years post-fire to test a series of hypotheses about the effects of fire on bacterial community composition. We ask questions on two themes: which factors control bacterial community composition during post-fire recovery, and how does the importance of different fire-responsive traits change during post-fire recovery? We find the following: Five years post-fire, vegetation community, moisture regime, pH, total carbon, texture, and burned/unburned all remained significant predictors of bacterial community composition with similar predictive value (R²). Bacterial communities became more similar to unburned sites five years post-fire, across the range of severity, suggesting resilience, while general structure of co-occurrence networks remained similar one and five years post-fire. Fast growth potential, as estimated using predicted 16S rRNA copy numbers, was no longer significantly correlated with burn severity five years post-fire, indicating the importance of this trait for structuring bacterial community composition may be limited to relatively short timescales. Many taxa that were enriched in burned sites one year post-fire remained enriched five years post-fire, although the degree to which they were enriched generally decreased. Specific taxa of interest from the genera Massilia, Blastococcus, and Arthrobacter all remained significantly enriched, suggesting that they may have traits that allow them to continue to flourish in the post-fire environment, such as tolerance to increased pH or ability to degrade pyrogenic organic matter. This hypothesis-based work expands our understanding of the post-fire recovery of soil bacterial communities and raises new hypotheses to test in future studies.

• Research Organization: Univ. of California, Oakland, CA (United States); Univ. of Wisconsin, Madison, WI (United States)
• Sponsoring Organization: USDOE Office of Science (SC); National Science Foundation (NSF)
• Grant/Contract Number: SC0016365; SC0020351; 2045864
• OSTI ID: 1977650
• Journal Information: Soil Biology and Biochemistry, Vol. 172, Issue C; ISSN 0038-0717
• Publisher: Elsevier
• Country of Publication: United States
• Language: English

Related Subjects

59 BASIC BIOLOGICAL SCIENCES
Agriculture
resilience
boreal forest
wildfire
burn severity
bacterial and archaeal communities