As a rapidly developing extreme drought event, flash drought poses an increasingly serious threat to agricultural production, ecosystem carbon sequestration, and regional ecological security. However, systematic understanding remains limited regarding the occurrence characteristics of flash drought across different cropland types and the mechanisms by which it affects gross primary productivity (GPP). Using root-zone soil moisture, meteorological variables, and GPP data for China from 2000 to 2020, this study characterized flash drought events across different cropland ecosystems, quantified the response frequency and intensity of GPP, and further explored the dominant driving factors using eXtreme Gradient Boosting and SHapley Additive exPlanations. The results showed that flash drought occurred more frequently in cropland than in non-cropland areas, and that rainfed cropland experienced flash drought more frequently and developed more rapidly than irrigated cropland. The mean GPP response frequency in cropland was 0.43, indicating that nearly half of flash drought events suppressed GPP. Regions with high sensitivity were mainly concentrated in northwestern and northeastern China, with northwestern China showing the lowest resistance to flash drought. Climatic background and hydro-meteorological anomalies were the dominant factors controlling GPP responses in cropland, and the dominant driving factors differed significantly among cropland types, exhibiting pronounced nonlinear and threshold effects. This study reveals the spatial heterogeneity and driving mechanisms of flash drought impacts across different cropland ecosystems in China and provides a scientific basis for agricultural drought-risk assessment and differentiated adaptive management.
Zhao et al. (Fri,) studied this question.