The impact of vegetation regeneration succession on soil carbon composition and enzyme activity in the southwestern karst region

> 0.05). β-1,4-glucosidase and cellobiohydrolase activities increased with succession, while dehydrogenase and catalase activities decreased. Random forest analysis identified carbon fractions as the dominant predictor of SOC variance (38%). Partial correlation analysis confirmed significant relationships between SOC, carbon fractions, and enzyme activities. Structural equation modeling showed that carbon fractions had the strongest direct effect on SOC accumulation, while soil nutrients had the largest total effect through indirect pathways, regulating enzyme activities and carbon fraction dynamics. These findings elucidate the pathways through which soil nutrients regulate SOC accumulation during karst vegetation succession, advancing understanding of carbon dynamics in degraded karst ecosystems.