A Health Assessment of Terrestrial Ecosystems in China Based on the Adaptive Indicator Reduction Method

Assessing terrestrial ecosystem health in China is crucial for guiding national economic strategies and ecological conservation. To address the lack of a unified national evaluation system, this study integrates the Pressure–State–Response (PSR) and Ecological Hierarchy frameworks to construct a five-layer network index system. A novel two-stage adaptive indicator reduction model is proposed, one which combines the TOPSIS method with an objective optimization model to select key indicators tailored to different ecoregions. Using this model, we evaluated the spatiotemporal dynamics of ecosystem health across China from 2001 to 2021. The results demonstrate the following: (1) The selected indicators effectively reflect regional ecological characteristics, with higher-weighted indicators aligning widely with the existing literature, demonstrating the system’s scientific validity and rationality. (2) Ecosystem health exhibits significant spatial variability, generally higher in the southeast and lower in the northwest. Over 21 years, health status remained relatively stable, with the improved areas (4.21%) primarily being located west of the Heihe–Tengchong line and north of the Qinling–Huaihe line, and exceeding the degraded areas.