Vegetation Restoration Enhances Aggregate‐Mediated Soil Organic Carbon Stabilization in Degraded Karst Landscapes of China: A Meta‐Analysis

ABSTRACT Soil aggregation is an important process linking vegetation restoration to soil organic carbon (SOC) accumulation in degraded karst landscapes, yet the aggregate‐mediated pathway remains insufficiently synthesized across restoration types and environmental conditions. We conducted a meta‐analysis of 213 paired observations from 57 studies in southwest China to evaluate changes in aggregate‐size distribution, aggregate stability, and SOC following cropland conversion to abandoned land, cash crop, grassland, shrubland, and forest. Vegetation restoration generally shifted aggregate‐size distribution from smaller (< 1 mm) toward larger (> 1 mm) fractions and increased SOC content, with the strongest SOC responses under forest and shrubland restoration. Across restoration pathways, the 2–5 mm aggregate fraction showed the most consistent relative importance for SOC, whereas the importance of other fractions varied among restoration types. Piecewise structural equation modelling identified aggregate stability as an important pathway linking vegetation restoration and environmental conditions to SOC response. These findings highlight the importance of restoration type and soil structural recovery when evaluating SOC accumulation in degraded karst landscapes.