Factors Influencing Landslide Susceptibility in Areas with High Vegetation Coverage

Numerous studies have confirmed the beneficial effects of vegetation on landslide control. However, shallow landslides remain common in densely vegetated areas, indicating that further research is necessary to fully understand the role of vegetation in reducing gravity-driven erosion hazards. In this study, we focused on a region with good vegetation cover (>65%) to further investigate how integrating vegetation and environmental factors (such as rainfall, lithology, and slope gradient) affect landslide susceptibility. The driving factors of landslide susceptibility under high vegetation conditions were examined at the macro level using a structural equation model and a geographic detector. The stability coefficient of a typical landslide was calculated at the micro-level by considering the effects of vegetation self-weight and artificial waste sediment. The results showed that vegetation, combined with rainfall and wind speed, increased landslide susceptibility, reflecting increases in high and very high susceptibility zones (21.30%), and decreases in low and very low susceptibility zones (42.71%). The combined effects of multiple factors had a greater influence than those of single factors. The strongest interaction was between slope gradient and rainfall (q = 0.81), followed by rainfall and lithology (q = 0.79). In saturated conditions, the reinforcing function of root systems was overwhelmed by the effect of tree vegetation self-weight. The slope stability significantly decreased compared to the conditions without load considerations. This study lays a foundation for identifying the dual role of vegetation in landslide control.