Spatiotemporal Evolution and Driving Mechanisms of Landscape Ecological Risks in a Typical Karst Watershed

Conducting landscape ecological risk (LER) assessments and identifying their driving mechanisms is a key approach to balancing regional development with ecological conservation and enhancing ecological security. Taking the Beipanjiang River Basin (Guizhou section)—a typical karst mountainous watershed—as the study subject, this research analyzed the spatiotemporal evolution of LER in the basin using landscape pattern indices and spatial autocorrelation analysis based on five sets of land-use data from 1985 to 2024. The optimal geographical detector (OPGD) was employed to identify the driving factors. The results are as follows: (1) From 1985 to 2024, the average LER index in the study area decreased by 37.07%. The proportion of the area classified as the lowest-risk zone increased from 18.76% to 38.83%, while the proportions of the medium-risk and higher-risk zones decreased to 14.97% and 3.55%, respectively, indicating an optimization of the ecological security pattern. (2) The center of gravity of the lowest-risk zones shifted northwestward, while the medium-risk and higher-risk zones contracted northeastward. The global Moran’s I ranged from 0.477 to 0.574. High–high clustering zones contracted in the north, and regional stress capacity decreased. Low–low clusters expanded in the south, forming a continuously consolidated ecological barrier zone. (3) The interactions between landscape fragmentation and factors such as elevation, precipitation, and NDVI all exhibited a two-factor enhancement effect, with the risk pattern being primarily driven by the synergy of multiple factors. This study provides a scientific basis for adjusting the land-use structure of the watershed, mitigating ecological risks, and promoting high-quality sustainable development.