A comprehensive framework for regional ecosystem health assessment: Integrating stability and distance to phase-optimal state.

A sound assessment of ecosystem health is critical for ecosystem management and ecological restoration. Existing approaches often fail to integrate temporal stability with a relative optimal benchmark, potentially limiting ecological diagnosis and restoration planning. We designed a ternary framework comprising Current Characteristics (CC), Stability (SI), and Distance to the phase-Optimal state (DO). Each dimension encompasses State, Pattern, and Function, forming a 3 × 3 assessment matrix that represents ecosystem structure, spatial patterns, and ecological functions. Applying the framework to the Hexi region of northwestern China, we assessed ecosystem health changes from 2000 to 2020. Regional ecosystem health improved by 18.97% over this period but exhibited pronounced spatial heterogeneity. The comprehensive health index exhibited a distinct hump-shaped pattern, with higher values in the central-southern region than at the eastern and western ends. This pattern was associated with water availability, ecological baseline conditions, land-use intensity, and human pressures. Relatively high health values occurred in and around Qilian Mountain National Park, whereas the northwestern desert areas generally had lower values. The assessment identified eight detailed management zones, which were further aggregated into four functional zones. Urgent Intervention Zone covered 47.28% of the region, mainly in the west, whereas Self-Sustaining Conservation Zone covered 11.03% and were concentrated in Qilian Mountain National Park. By distinguishing current conditions, temporal stability, and proximity to the phase-optimal state, the framework supports differentiated restoration prioritization, spatial zoning, and monitoring of ecological management outcomes. It provides a potentially transferable approach to regional ecosystem health assessment and management.