Improvement in vegetation ecological quality and its driving factors in China over 2001-2024.

Against the backdrop of China's ecological civilization and carbon-neutrality goals, it is essential to clarify how vegetation ecological quality index (EQI) has changed and what drives it. Based on remote sensing products, this study reveals that China's EQI increased significantly at a rate of 0.106 yr-1 during 2001-2024, corresponding to an overall increase of approximately 9%. Unlike previous studies that focused on normalized difference vegetation index or net primary productivity and considered only climate and land use change, this study explicitly incorporates atmospheric CO2 and nitrogen deposition into a nationwide attribution framework for EQI. Human activities explain 50.1% of EQI changes, while environmental factors collectively contribute 49.9%, dominated by atmospheric CO2 growth (42.8%), with smaller contributions from nitrogen deposition (4.5%) and climate change (2.7%). Overall, China's EQI has significantly improved over the past two decades, primarily driven by vegetation restoration associated with ecological projects and increasing atmospheric CO2 concentration. Spatially, improvements were most pronounced in western and northern China, while parts of the southeastern coast and high-elevation alpine regions exhibited stagnation or degradation. This study provides new attribution evidence for evaluating the effectiveness of ecological projects and formulating regionally differentiated ecological management and climate adaptation strategies.