Forest Conversion Changes Soil Particulate Organic Carbon and Mineral-Associated Organic Carbon via Plant Inputs and Microbial Processes

Primary forest conversion greatly influences soil organic carbon (SOC) sequestration. However, our understanding of how primary affects SOC fractions and chemical component evenness remains limited. We examined (from mixed broadleaved Korean pine to secondary coniferous plantation) free particulate OC (POC), aggregate-occluded POC, mineral-associated (MAOC), their via plant inputs (e.g., litter fine roots) microbial properties biomass residue C) in Northeast China. led a large increase root quality (lower C/N ratio), SOC, MBC forests reduction quantity quality, MBC, C plantations, which drove changes POC MAOC. As result, after forests, decreased by 20.3% increased 57.2%. After 49.1%, while MAOC 42.4% 9.0%, respectively. Free was negatively correlated with biomass. Aggregate-occluded were positively C. Meanwhile, the components O-alky being higher aromatic lower, not affected conversion. The associated that High-quality benefit sequestration aggregates MAOM through assimilation accumulation Future management should consider tree species high-quality input as possible compensation for climate change sequestering more aggregates.