Rainfall partitioning and contrasting local understory runoff and soil loss responses among three vegetation communities in a karst restoration area

Study region Puding County, southwestern China, a karst area characterized by severe rocky desertification and long-term ecological restoration. Study focus Vegetation restoration alters canopy structure and rainfall redistribution, but how these changes relate to localized understory runoff and soil loss remains unclear. We monitored 31 rainfall events in three vegetation communities dominated by Platycladus orientalis , Platycarya strobilacea , and Viburnum dilatatum . Community-scale throughfall, stemflow, and canopy interception were quantified, while runoff and soil loss were monitored in subcanopy and stem-base microplots. Mixed-effects models were used to assess rainfall, microsite, and environmental associations. New hydrological insights for the region Throughfall was the largest rainfall-partitioning component and was highest in P. orientalis (86.21%), although this community did not show the strongest erosion response. P. strobilacea had the greatest runoff and soil loss, with mean soil loss of 28.97 and 61.79 g m⁻² in subcanopy and stem-base microsites, respectively. Gross rainfall showed strong nonlinear associations with runoff and soil loss. Slope and bare-soil cover were positively associated with both responses, whereas saturated hydraulic conductivity was negatively associated. After accounting for gross rainfall, community-level throughfall fraction provided no significant additional explanatory information for subcanopy runoff or soil loss. Because stemflow to individual stem-base microplots was not directly measured, stem-base responses were interpreted as integrated microsite responses.