Ecosystem health responses to impervious surface expansion along a dynamic urban-rural gradient in China's Loess...

Rapid urbanization-induced impervious surface expansion (ISE) poses substantial threats to regional ecosystem health (EH). Understanding spatiotemporal EH variations and their response to ISE is crucial for sustainable urban development. However, existing studies have mainly focused on urban areas or static models, leaving the dynamic response of EH to ISE along urban-rural gradients poorly understood, especially in ecologically fragile areas such as China's Loess Plateau (CLP). This study aims to use the vigor-organization-resilience-services (VORS) framework, which comprehensively considers ecosystem integrity, to quantify the EH of CLP between 2000 and 2022 and analyze its response to urbanization development intensity (UDI) along the dynamic urban-rural gradient. During this period, both the UDI and EH index (EHI) increased, with corresponding rate of increase of 0.074%·yr^-1 and 0.001·yr^-1. High UDI clustered around provincial capitals. In contrast, regions exhibiting higher EHI (> 0.55) occurred mainly in the east-central CLP, while regions characterized by lower EHI (< 0.45) were concentrated in the northwest and southeast. Spatial analysis indicates that UDI and EHI are significantly negatively correlated spatially. From a dynamic urban-rural gradient perspective, EHI declined with increasing UDI, with marked spatial heterogeneity in the magnitude and direction of changes among cities. The findings offer a novel perspective for understanding the spatial heterogeneity of ISE impacts on EH, thereby supporting tailored ecological conservation and sustainable development in the CLP.