[Spatial-temporal Evolution and Driving Factors of Ecosystem Health in the Jialing River Basin]

As a key ecological barrier in the upper reaches of the Yangtze River， the Jialing River Basin plays a crucial role in coordinating ecological protection and regional development within the Yangtze River Economic Belt. Based on the "vigor-organization-resilience-services （VORS）" model， this study assesses the spatiotemporal evolution of ecosystem health in the Jialing River Basin from 2000 to 2022. By integrating terrain gradient analysis， spatial autocorrelation analysis， and the XGBoost-SHAP model， the study further reveals the differentiation characteristics of ecosystem health along terrain gradients and its driving mechanisms. The results show that： ① From 2000 to 2022， the ecosystem health index in the Jialing River Basin showed an overall upward trend， with a spatial pattern of "high in the central region and low in the north and south，" and significant spatial clustering， mainly in the form of high-high and low-low clusters. ② In the vertical dimension， ecosystem health exhibited significant differentiation along terrain gradients， with lower health levels in low-gradient areas and higher health levels in high-gradient areas. ③ The results of the XGBoost-SHAP model indicate that natural factors had a far greater influence on ecosystem health in the Jialing River Basin than that of socioeconomic factors， with vegetation cover identified as the most critical factor. ④ There were generally significant nonlinear relationships and threshold effects between the influencing factors and ecosystem health.