Impacts of Human Activities on Ecosystem Services in Watersheds: Evidence from the Taihu Lake Basin, China

Human activity intensity has become an increasingly significant driver of changes in ecosystem services, and understanding their spatiotemporal relationships is essential for watershed ecological governance. Taking the Taihu Lake Basin as the study area, this research utilizes multi-source geospatial data from 2003 to 2023. The InVEST model is employed to assess four key ecosystem services: water yield, soil conservation, carbon storage, and habitat quality. A human activity intensity (HAI) index is constructed using the entropy-weight method, while bivariate spatial autocorrelation and geographically weighted regression are applied to disentangle the spatiotemporal evolution, spatial associations, and local variations in the associations between HAI and ecosystem services. The results indicate that (1) HAI has continuously intensified, with high-intensity areas undergoing an approximately 9.5-fold expansion and exhibiting a distinct “high in the east, low in the west” pattern; (2) carbon storage and habitat quality show persistent declines, whereas water yield and soil conservation exhibit fluctuating upward trends, with an overall “high in the southwest, low in the northeast” distribution; (3) HAI is significantly positively correlated with water yield and negatively correlated with carbon storage, soil conservation, and habitat quality, with 2018 identified as a critical turning point; and (4) the associations exhibit notable spatial non-stationarity, with the proportion of significant grid cells following a hierarchical order of habitat quality > water yield > carbon storage > soil conservation. Zones with strong regression coefficients occur only as localized patches, while the majority of the basin is characterized by low-to-moderate driving intensity. This study further reveals three core mechanisms—land-use path dependence, policy-induced threshold responses, and spatial spillover associations—providing a scientific basis for differentiated ecological management and sustainable development in the Taihu Lake Basin.