Effects of biochar on soil carbon pool stability in the Dahurian larch (Larix gmelinii) forest are regulated by the dominant soil microbial ecological strategy

Biochar is widely used in integrated soil management, and can directly alter the soil environment and drastically affect the soil microbial community. Given the important role of soil microorganisms in the carbon cycling of soils, it is important to understand how biochar alters the stability of soil organic carbon (SOC) pools in Dahurian larch (Larix gmelinii) forests through microbial pathways unburned and high-severity burned soils to guide comprehensive soil management and restore ecological functions in postfire soils. This study employed the r/K ecological strategy theory to quantify the ecological strategy propensities of soil microbial communities. The ratio of oligotrophic species to copiotrophic species was used to measure these propensities. The study aimed to establish a link between the ecological strategy choices of microbial communities and SOC pools. We found: that (1) biochar increases the mass of SOC regardless of whether the soil has experienced fire, (2) biochar addition to unburned stands makes the K-strategy dominant in microbial communities, significantly decreasing the mineral-associated organic carbon (MAOC) to SOC ratio and weakening the of SOC pool stability; (3) biochar addition to high-severity burned stands shifts the dominant microbial strategy to r-strategy, restoring the damaged microbial community to its preburned state. The MAOC/SOC ratio significantly increased, contributing to the restoration of the SOC pool stability and enhancing the soil carbon sequestration capacity. This study elucidates the effects of biochar addition on the dominant ecological strategy of microbial communities and alterations in the structure and stability of SOC pools, which is important for understanding how biochar affects SOC pools through biochemical pathways, and provides important references for unraveling the relation between microbial ecological strategies and soil carbon pools.