Response of ecosystem productivity and stability to flash droughts across moisture gradients in China

Flash droughts, characterized by sudden onset and rapid intensification, pose a considerable threat to terrestrial ecosystems. However, the interactive impacts of flash drought characteristics on ecosystem productivity and the mechanisms governing ecosystem stability across China's diverse hydroclimatic regions remain unclear. Using the ERA5-Land and GOSIF datasets, we identified flash drought events during 1980–2020 from soil moisture data using a quantile approach and quantified ecosystem stability by integrating the magnitude and duration of productivity losses. Both flash drought frequency and affected area increased significantly over the past four decades, especially after 2000. Flash droughts reduced ecosystem productivity across 58% of the study area, and their characteristics magnified the losses in a combined amplifying pattern. Forests generally maintained high resilience across regions, whereas grasslands in the semi-arid and sub-humid regions of China exhibited the lowest resistance and resilience, and experienced the largest productivity declines. Productivity anomalies during drought periods reliably indicated ecosystem resistance, whereas recovery times better reflected resilience. These findings advance our understanding of ecosystem responses to flash droughts, and underscore the critical need for appropriate resistance−resilience assessment frameworks.