Cellulase Dominates Soil Organic Carbon Dynamics Under Plant Detritus Input in Forest Ecosystems

Soil carbon-degrading enzymes mediate terrestrial carbon cycling, yet their roles in driving SOC dynamics under altered plant detritus inputs lack global quantification. Using 564 observations across global forest biomes, we systematically evaluated impacts of detritus input regimes on carbon-degrading enzymes and SOC dynamics, as well as their linkages. Double litter enhanced cellulase without affecting SOC content and ligninase activities. In contrast, all detrital removal treatments significantly suppressed cellulase activity and reduced SOC pools, with no root exerting the strongest effect. Cellulase activity was the main driver of SOC responses, modulated by forest type and experimental duration. Initially, SOC regulation differed between two forests (i.e., microbial biomass dominated in coniferous, litter inputs dominated in broad-leaved forests), but over time (> 2 years), shifted to cellulase dominance in both forests. Collectively, our findings improve predictions of soil C dynamics under climate change and support the management of forests as effective C sinks.