Effects and mechanisms of moss cover reducing surface runoff and soil erosion compared to pine needle litter on karst slopes

Study region Huaxi District, Guiyang City, Guizhou Province, southwestern China. Study focus Karst regions have experienced severe rocky desertification from intense weathering and soil erosion, threatening regional ecological security. However, systematic comparisons of soil and water conservation effects of different surface covers (moss and pine needle) on karst slopes remain insufficient. The study established runoff plots on karst slopes in Guizhou. It monitored soil water content dynamics at 5 cm and 15 cm depths under moss cover and pine needle litter across different rainfall types and slope gradients. We also recorded runoff and sediment loss during erosive rainfall events. New hydrological insights for the region Moss cover exhibited more stable and higher soil water retention at 15 cm depth, pine needle cover showed greater sensitivity to moisture changes at 5 cm depth. Moss achieved significantly better runoff and sediment reduction than pine needles, with average reductions of 27.176% in runoff coefficient and 58.840% in soil erosion. Heavy rainfall and steeper slopes intensified runoff and sediment loss, moss maintained effective soil and water conservation performance. Predictions based on XGBoost and RUSLE models indicated high accuracy in runoff, sediment loss prediction was unstable due to multiple influencing factors. These included rainfall, slope, cover type, and antecedent moisture, as well as complex nonlinear processes by these factors. Moss cover has significant advantages for ecological restoration in karst regions.