Decoupling of vegetation greenness and resilience reveals hidden risks in China's protected areas.

Vegetation greenness and ecosystem resilience reflect different dimensions of ecosystem functioning. While recent global studies have documented widespread greening alongside declining resilience, the extent to which protected areas-as the cornerstone of conservation policy-can effectively maintain both dimensions remains inadequately quantified at the national scale, particularly for China's extensive protected area network. Here we evaluate the effectiveness of China's protected areas from both perspectives using long-term remote sensing time series (1982-2022) and a counterfactual matching framework that controls for environmental covariates and pre-establishment trends. At the national scale, we find a partial decoupling between greenness and resilience: vegetation greenness has increased substantially over recent decades, while ecosystem resilience has exhibited an overall declining trend. Among the 307 protected areas examined, joint evaluation identified only 84 sites exhibiting significant effectiveness in both greenness- and resilience-based assessments, revealing that assessments based solely on vegetation greenness may overlook latent risks associated with declining ecosystem recovery capacity. Driver analysis indicated that canopy height and protected area size were positively associated with greenness effectiveness, whereas resilience-based effectiveness was primarily associated with baseline ecosystem conditions. By jointly considering greenness and resilience within a counterfactual framework, this study provides empirical evidence to inform adaptive management and the ongoing optimization of China's protected area system.