Heterogeneous effects of aerosols on terrestrial ecosystems in China

Ecological impacts of aerosols on vegetation remain highly uncertain due to their capacity for both modifying radiation and causing phytotoxic damage. China has experienced the most rapid air quality improvement globally since 2013, yet the ecosystem consequences of this governance are poorly quantified. Here, we analyzed satellite observations and reanalysis data from multiple sources covering a long period to investigate the spatiotemporal intereactions between aerosols and vegetation across China. By employing generalized linear mixed models (GLMM), we isolated the independent and relative contributions of aerosol optical depth (AOD) to vegetation dynamics. Our results reveal a pronounced divergence between the north and south: AOD suppresses vegetation growth in southern China with limited radiation, while in regions limited by water availability, it likely enhances water use efficiency and productivity by reducing surface radiation and vapor pressure deficit (VPD), thereby curtailing transpiration water loss. The impacts exhibited diverse patterns across species: needleleaf forests, meadows, wetlands, and shrublands demonstrated heightened vulnerability to aerosol suppression, whereas needleleaf and broadleaf mixed forests uniquely benefited from increased diffuse radiation. Notably, the gross primary productivity (GPP) of steppe ecosystems underwent a fundamental shift from a negative to a positive response to aerosols after 2013, highlighting the dynamic interactions between aerosols and ecosystems that were specific to the environment. Crucially, the GLMM quantified a significant weakening of the aerosol suppression effect after the implementation of clean air policies, with its standardized negative coefficient on GPP declining from −0.16 to −0.10. This study provides observational evidence on a large scale that improving air quality not only alleviates environmental stress but also directly promotes ecosystem function, offering critical insights for assessing carbon neutrality policies.