Plant above-ground biomass drives the recovery of soil microbial communities in a subtropical-temperate transition zone following forest wildfire

Wildfire profoundly reshapes soil microbial community structure and function, thereby modulating biogeochemical processes in natural ecosystems. However, the extent to which post-fire vegetation restoration influences these microbial communities in forest soils remains insufficiently characterized. To address this knowledge gap, a chronosequence approach spanning post-fire intervals of 1, 6, 13, and 29 years was employed to assess shifts in microbial composition, biomass, and community structure in subtropical-temperate ecotonal forests of Central China. The findings indicate temporal fluctuations in microbial biomass , including microbial biomass carbon, nitrogen, and PLFA contents, with significant declines observed exclusively in the first year post-burn. These variations were primarily regulated by above-ground biomass and dissolved organic carbon. Microbial community structure exhibited dynamic responses to fire, with an increased gram-positive to gram-negative bacterial ratio and a rise in the cyclopropyl to precursor (cyc/pre) ratio during the early post-fire period. However, the fungi-to-bacteria ratio remained stable across the 29-year chronosequence. The elevated cyc/pre ratio was largely attributable to reductions in above-ground biomass, which altered resource availability and microbial interactions. Notably, fungal communities exhibited more prolonged shifts than bacterial communities , suggesting lower resilience to wildfire disturbances. These results highlight above-ground biomass as a critical determinant in the post-fire recovery trajectory of soil microbial communities. • Wildfire significantly decreased microbial biomass within short-term recovery period. • Spatiotemporal variations were found in microbial community structure. • Plant above-ground biomass mediated microbes along post-fire time. • Fungi had lower resilience to wildfire compared with bacteria.