The multi-scale heterogeneity of habitat quality changes in the Heihe River basin

Habitat heterogeneity in inland river basins constitutes a dynamic and structured ecological pattern governed by hydrological processes and expressed across multiple temporal and spatial scales. Understanding and conserving this heterogeneity is crucial for ensuring ecological security and promoting sustainable socio-economic development in the arid regions of northwestern China. Drawing upon the general characteristics of inland river basins, this study establishes a theoretical analytical framework to examine habitat quality differentiation across mountainous, oasis, and desert ecosystems. And based on the spatial heterogeneity of oases, they are classified into three geomorphic zones: the Higher Position Oasis (HPO), the Middle Position Oasis (MPO), and the Lower Position Oasis (LPO). This study employs the Habitat Quality module of the InVEST model to conduct a systematic spatiotemporal assessment of habitat quality dynamics across two nested ecological scales: the entire inland river basin and its constituent oasis systems. Key findings are as follows: (1) Habitat quality exhibits a consistent spatial gradient at the basin scale—mountainous areas > oases > desert—while within the oasis system, it declines along a gradient from HPOs to MPOs and LPOs. (2) Although habitat quality remains relatively stable over time, localized degradation is observed, with mild, moderate, and severe deterioration predominantly concentrated in medium-productivity oases. Collectively, this research advances methodological rigor in habitat quality assessment for arid inland river basins and offers empirically grounded insights to inform ecosystem conservation strategies and early-warning frameworks for basin–oasis coupled systems.