Divergent driving mechanism of land uses on soil erodibility between different soil types in the ecological zone of Three Gorges Reservoir Area.

Soil erodibility is a vital parameter utilized for soil erosion prediction, yet its variability remains poorly understood due to complex interactions between soil properties and land use types. To address this gap, six typical land uses of slope farmland (SF), broad-leaved forest land (BF), coniferous forest land (CF), orchard (O), shrubland (S), and grassland (G) were selected across two dominant soil types (yellow and purple) in the Three Gorges Reservoir Area. Seven soil erodibility indicators and a comprehensive soil erodibility index (CSEI) were quantified and the differential influencing mechanism of soil erodibility among different soil and land use types were identified. The results indicated that soil erodibility varied greatly with soil and land use types. Soil erodibility of soil cohesion, penetration resistance, mean weight diameter, mean number of drop impact, soil erodibility of K factor and structural stability index of yellow soil were greater than those of purple soil, whereas the opposite results were found in saturated conductivity and CSEI. Overall, CSEI of slope farmland and orchard were significantly greater than that of other land uses. CSEI was significantly correlated with soil and vegetation properties for both soil types, but their influencing mechanism of land uses on CSEI was completely different between these two soil types. For yellow soil, variations in CSEI among different land uses were dominantly controlled by plant root mass density (RMD) via its direct effect and indirect effect through decreasing bulk density (BD) and increasing organic matter content (SOM). However, that for purple soil was dominantly controlled by Clay content via its direct effect and indirect effect through increasing SOM and WSA. Our findings suggest that land use policies in the Three Gorges Reservoir Area should prioritize orchard and slope farmland management to mitigate erosion. These results also insight into our understanding of soil-land use interactions on soil erodibility and provide the theoretical basis for soil erosion prevention and vegetation restoration strategies formulation in the Three Gorges Reservoir Area.