Response of vegetation ecological water requirement to landscape evolution: From non-linear regulation to critical sensitive zones

The intensification of global environmental change has accelerated the reorganization of terrestrial landscapes. Such structural variations inevitably alter local climatic conditions and ecosystem functions, thereby governing the spatiotemporal distribution of ecological water requirement (EWR). However, the non-linear constraining effects of landscape spatial configuration on vegetation EWR remain underexplored. This study characterized landscape pattern evolution in the Ziya River Basin (ZYRB) and applied a SHAP-interpreted random forest model to decouple its regulatory effects on EWR. Furthermore, a comprehensive framework for sensitivity analysis was developed to identify critical thresholds and sensitive zones. Results indicated a distinct trend toward landscape fragmentation and diversification from 1990 to 2023. The increased patch fragmentation, shape complexity, and diversity, particularly the Fractal Dimension Index ( r = −0.73) was associated with reduced EWR, whereas heightened structural connectivity amplified water demand. Spatially, climatic factors dominated the heterogeneity of EWR, accounting for about 64% of the total importance. Among the landscape pattern indices, the Fractal Dimension Index (FRAC) and Patch Cohesion Index (COHESION) emerged as the leading modulators, with each explaining approximately 9% of the total variance. The response of EWR to landscape drivers exhibited the U-shaped or fluctuating trends rather than simple linearity. The meteorologically sensitive zones identified based on the thresholds were predominantly concentrated in mountain-plain ecotones and groundwater over-exploited regions distributed along a northeast-southwest strip extending across eastern Shijiazhuang and central Handan City. Landscape -sensitive zones coincided with regions of high structural complexity, which were clustered in the western parts of Shijiazhuang and Xingtai City, as well as in Yangquan City. These insights underscore the critical role of landscape complexity in buffering water stress and provide the spatially explicit scientific basis for formulating water regulation measures and land management strategies. The proposed framework possesses broad applicability for diagnosing constraint mechanisms and delineating critical zones in diverse ecological contexts.