Lithology-mediated soil erodibility characteristics after vegetation restoration in the karst region of Southwest China

Ecological restoration projects have significantly increased global vegetation cover and reduced soil erosion. However, it is very challenging to clarify the complex soil erosion mechanisms of limestone and dolomite in the southwest karst region and to identify the key factors affecting erosion. The study site has a subtropical monsoon climate with precipitation concentrated during the rainy season from May to September. In this study, four plantation restoration measures with a recovery time of approximately 16 years were selected, which included arbor forest, orchard, grassland, and cropland (control). Soil physical-chemical properties and soil erodibility K values were used to evaluate the soil erosion characteristics. The results showed that both limestone and dolomite exhibited lower soil bulk density as well as higher capillary porosity, and soil water-stable aggregates after revegetation. The limestone and dolomite K values were reduced by 12%-15% and 15%-17%, respectively. However, the K value of limestone was 17.9% higher than that of dolomite, indicating that dolomite exhibited a higher stability. Through redundancy analysis and structural equation modeling, revegetation was found to reduce soil erosion by influencing the soil particle composition. The silt was the key factor influencing soil erosion, accounting for 84.4% and 78.2% of the variation in the limestone and dolomite K values, respectively. These findings suggest that vegetation restoration enhances soil erosion resistance; however, the effectiveness of restoration is controlled by the lithology in the southwest karst region. These findings provide a reference for soil and water management and vegetation restoration.