Research on the Response and Driving Mechanisms of Soil Organic Carbon Storage in Different Grassland Types to Enclosure Management

Abstract

Slight variations in soil organic carbon (SOC) stocks critically influence atmospheric CO₂ levels and global carbon-climate feedback. While enclosure practices effectively restore degraded grasslands by excluding livestock disturbances, their ecosystem-specific regulatory mechanisms on SOC storage remain unresolved. This study aims to decode type-dependent SOC control pathways across contrasting grassland ecosystems under enclosure management. We investigated 9-year enclosure gradients through integrated analysis of plant communities, soil properties, and microbial biomass in three archetypal grasslands (temperate desert, steppe, mountain meadow) in Xinjiang, China. Partial least squares path modeling (PLS-PM) quantified hierarchical drivers of SOC dynamics across ecosystems. Enclosure induced divergent restoration trajectories: promoted plant recovery in steppes/meadows (P < 0.05) but degraded desert vegetation. Surface SOC increased in deserts through abiotic amelioration (path = 0.82), while decreased in meadows due to microbial biomass collapse (path = 0.90). Steppes exhibited soil-microbe co-regulation (path = 0.65 vs. 0.31) with intermediate SOC sensitivity. PLS-PM revealed ecosystem control hierarchies shifting from edaphic dominance (deserts) to microbial mediation (meadows). Enclosure effectiveness is governed by ecosystem-specific SOC drivers and temporal thresholds (5–15 years). We propose type-optimized protocols: desert systems require < 10-year enclosure with windbreak vegetation, steppes need 10–15 years with rotational grazing, while meadows demand > 15-year enclosure plus microbial augmentation. This mechanistic framework advocates precision grassland engineering that aligns management duration with dominant SOC pathways (abiotic/microbial/phased), advancing climate-smart carbon governance in arid lands.