近40年中国植被绿度对干旱胁迫的响应及其驱动因素OACHSSCD

In the context of global warming,the increasing frequency of extreme weather events has led to more frequent and intense droughts in China,intensifying vegetation changes and emerging as a prominent issue in ecosystem risk management.Persistent droughts have profoundly influenced vegetation dynamics,carbon cycling,and ecosystem stability,emphasizing the urgent need to better understand vegetation sensitivity to climatic stressors.To address this,the Normalized Difference Vegetation Index(NDVI),land use,and ERA5—Land datasets were integrated,and linear regression,run theory,the vegetation sensitivity index,and a random forest model were employed to comprehensively investigate the sensitivity of vegetation greenness to drought stress and its driving factors.The analysis revealed the spatiotemporal dynamics of vegetation greenness over the past four decades across China and identified the optimal time scale for characterizing drought events.It further quantified vegetation sensitivity to drought stress and examined the effects of key biophysical drivers during drought periods.The results showed that vegetation in China generally exhibited a restorative growth trend over the past 40 years,with annual NDVI change rates ranging from-0.0140 to 0.0088/a.The southeastern region demonstrated clear improvement,whereas the northwestern region displayed a mixed pattern of recovery and degradation,reflecting the combined influences of climate change and human activities.At the optimal drought time scale,vegetation responses to drought stress exhibited a spatially heterogeneous pattern of"long—term in the northwest and short—term in the southeast."Most regions experienced frequent and severe drought events,with durations lasting up to 24 months and maximum severity values reaching 33.50,indicating persistent hydroclimatic stress in arid and semi—arid zones.Vegetation anomalies and sensitivity showed a distinct southeast—northwest gradient.High sensitivity values(mean up to 1.15)and low anomaly values were concentrated in ecologically fragile areas such as the arid northwest and the Tibetan Plateau,where sparse vegetation and hyper—arid ecosystems were particularly sensitive to drought stress.Vegetation sensitivity was mainly influenced by precipitation(26.61％),solar radiation(25.00％),and soil moisture(17.36％).On the Tibetan Plateau,compound impacts of multiple climatic drivers were evident,and the synchronous occurrence of drought and these factors caused ecological impacts far exceeding the cumulative effects of single events.These findings highlight the necessity of integrating temporal drought characteristics and compound stress interactions into vegetation risk assessment frameworks.This integration can improve the accuracy of drought sensitivity prediction and provide scientific guidance for climate adaptation and sustainable ecosystem management in China.