Recovery patterns of soil bacterial and fungal communities in Chinese boreal forests along a fire chronosequence

Wildfire has profound and pervasive consequences for forest ecosystems via directly altering soil physicochem-ical properties and modulating microbial community. In this study, we examined the changes in soil properties and microbial community composition and structure at different periods after highly severe wildfire events (44 plots, 113 samples) in the Chinese Great Khingan Mountains. We also separated charcoal from burnt soils to establish the relationship between microbial community structures in soils and charcoal. We found that wild -fire only significantly altered bacterial and fungal beta-diversity, but had no effect on microbial alpha-diversity across a 29-year chronosequence. The network analysis revealed that the complexity and connectivity of bacterial and fungal communities were significantly increased from 17 years after fire, compared with either unburnt soils or soils with recent fires (0-4 years after fire). Differential abundance analysis suggested that bacterial and fungal OTUs were enriched or depleted only during 0-4 years after fire compared with the unburnt soils. In addition, soil pH, dissolved organic C and dissolved organic N were key determinants of soil bacterial and fungal communities during 17-29 years after fire. The fire-derived charcoal provided a new niche for microbial colonization, and mi-crobes colonized in the charcoal had a significantly different community structure from those of burnt soils. Our data suggest that soil bacterial and fungal communities changed significantly during the recovery from fire events in terms of the abundance and co-occurrence networks in the boreal forest ecosystems. (c) 2021 Elsevier B.V. All rights reserved.

Automated summary

Wildfires have significant and long-lasting impacts on forest ecosystems by altering soil properties and microbial communities. This study in the Chinese Great Khingan Mountains found that wildfires only significantly affected bacterial and fungal beta-diversity over a 29-year period. Additionally, soil properties like pH, dissolved organic C, and N played key roles in determining soil bacterial and fungal communities post-fire.