Assessing soil detachment driven by root-soil interactions in karst trough valleys: Influence of vegetation restoration on erosion-deposition contrasts

Background and aimsVegetation restoration duration and topographic position (erosion vs. deposition) influence soil detachment capacity ( Dc ) in karst trough valleys by altering hydraulic conditions, soil physicochemical properties, and root traits. This study evaluates the controlling and mitigating effects of vegetation restoration duration and topographic position on soil detachment capacity in a karst trough valley environment.MethodsTwo grasslands with 5-year and 10-year vegetation restoration durations, along with severely degraded bare land as a control, were selected from erosion and deposition sites. Soil properties, root traits, and Dc under three flow discharges (60, 80, and 100 L·min⁻¹) were measured. Relationships between Dc and influencing factors were evaluated using Pearson correlation, curve fitting, and partial least squares path modeling (PLS-SEM).ResultsCompared with A5, A10 exhibited significantly higher water-stable aggregates (WSA), soil organic matter (SOM), mean root diameter (RD) and root volume density (RVD). Furthermore, each parameter was consistently greater at deposition sites than at erosion sites. Dc declined significantly with increasing restoration age, except on the bedding slope of erosion site. The mean Dc at erosion sites was 3.56 times higher than at deposition sites. Stream power was the strongest hydraulic predictor of Dc . Regardless of topographic position, Dc was negatively correlated with bulk density (BD), WSA, SOM and RVD.ConclusionThe results showed that SOM, WSA, root diameter, and RVD increased with restoration time. Stream power best predicted Dc among hydraulic parameters. Soil properties primarily controlled Dc at erosion sites, while hydraulic factors dominated at deposition sites.