soil detachment capacity

Vegetation restoration duration and erosion and deposition topography influence the soil detachment capacity (Dc) through changes in hydraulic conditions, soil properties and root traits. However, owing to its unique geological structure, the mechanism of soil detachment at erosion and deposition sites in karst trough valleys following the “Grain for Green” project remains unclear. Therefore, at erosion and deposition sites, we selected 5 years (A5) and 10 years (A10) of grassland for vegetation restoration as the research objects, whereas bare land was used as the control. The change mechanism of Dc was analyzed by conducting indoor scouring experiments at flow discharges of 60, 80, and 100 L·min−1. The results demonstrated that the water-stable aggregate (WSA), soil organic matter (SOM), root diameter (RD) and root volume density (RVD) of A10 were greater than those of A5, and these parameters at deposition site were greater than at erosion site. Except for the bedding slope of erosion site, Dc showed a significant decreasing trend as the duration of vegetation restoration increased. The average Dc of erosion site was 3.56 times greater than the Dc observed at the deposition site. Furthermore, stream power was the optimal hydraulic parameter for describing Dc in karst trough valley. The Dc at erosion and deposition sites exhibited a significantly negative correlation with BD, WSA, SOM, and RVD. Moreover, the vegetation restoration duration and topography had indirect effects on Dc. The primary drivers of variations in Dc were identified as soil properties at erosion site and hydraulic conditions at deposition site.