Landscape connectivity significantly influences the spatial spillover effects of soil erosion: Based on examples from typical karst watersheds

• The spatial dependence and spillover effects of soil erosion in karst areas were revealed from a sub-watershed perspective. • The optimized RUSLE model using karst desertification factors improves the estimation accuracy of soil erosion in karst areas. • Landscape connectivity is the main determinant of spatial spillovers of soil erosion. • Landscape patterns' influence on soil erosion is complex, mainly driven by the number of patches and landscape diversity. Soil erosion is a key environmental issue impacting terrestrial ecosystems, especially in sensitive karst regions. Although it is generally accepted that soil erosion processes are strongly influenced by changes in land use and landscape patterns, there is still uncertainty about the spatial association between soil erosion and landscape patterns, especially when spatial spillover effects are considered. To tackle this problem, this study incorporates a karst desertification factor to optimize the commonly applied Revised Universal Soil Loss Equation (RUSLE) model. Based on this, we investigated soil erosion(SE) and landscape characteristics in two representative karst basins in southern China: the Yeji River (YJR) and Dabang River (DBR) watersheds. Finally, for the first time at the sub-watershed scale, we used spatial econometric modeling to resolve the spatial dependence of soil erosion and investigated the spatial association between landscape and SE. The findings showed SE tended to increase in both watersheds during the study period, with high erosion areas concentrated in the middle and lower reaches of watersheds. Disturbed by natural and anthropogenic activities, the watershed landscape exhibits a general trend toward fragmentation. Spatial econometric analysis confirmed the significant presence of SE spatial spillovers, highlighting the importance of interactions between sub-watersheds. Furthermore, the spatial relationship between the landscape patterns and SE demonstrated their complexity, with landscape connectivity significantly influencing the spatial spillover effects of SE. These findings deepen our comprehension of the drivers of soil erosion in ecologically fragile regions and provide support for regional landscape management and soil preservation efforts.