State Key Laboratory of Water Resources Engineering and Management, Wuhan University, Wuhan 430072, PR China.
Changjiang Water Resources Protection Institute, Wuhan 430051, PR China; Key Laboratory of Ecological Regulation of Non-point Source Pollution in Lake and Reservoir Water Sources, Changjiang Water Resources Commission, Wuhan 430051, PR China.
Sci Total Environ. 2024 Jun 25;931:172926. doi: 10.1016/j.scitotenv.2024.172926. Epub 2024 May 1.
Flash droughts characterized by rapid onset and intensification are expected to be a new normal under climate change and potentially affect vegetation photosynthesis and terrestrial carbon sink. However, the effects of flash drought on vegetation photosynthesis and their potential dominant driving factors remain uncertain. Here, we quantify the susceptibility and response magnitude of vegetation photosynthesis to flash drought across different ecosystems (i.e., forest, shrubland, grassland, and cropland) in China based on reanalysis and satellite observations. By employing the extreme gradient boosting model, we also identify the dominant factors that influence these flash drought-photosynthesis relationships. We show that over 51.46 % of ecosystems across China are susceptible to flash drought, and grasslands are substantially suppressed, as reflected in both sensitivity and response magnitude (with median gross primary productivity anomalies of -0.13). We further demonstrate that background climate differences (e.g., mean annual temperature and aridity) predominantly regulate the response variation in forest and shrubland, with hotter/colder or drier ecosystems being more severely suppressed by flash drought. However, in grasslands and croplands, the differential vegetation responses are attributed to the intensity of abnormal hydro-meteorological conditions during flash drought (e.g., vapor pressure deficit (VPD) and temperature anomalies). The effects of flash droughts intensify with increasing VPD and nonmonotonically relate to temperature, with colder or hotter temperatures leading to more severe vegetation loss. Our results identify the vulnerable ecological regions under flash drought and enable a better understanding of vegetation photosynthesis response to climate extremes, which may be useful for developing effective management strategies.
快速发生和增强的闪发性干旱预计将成为气候变化下的新常态,并可能影响植被光合作用和陆地碳汇。然而,闪发性干旱对植被光合作用的影响及其潜在的主导驱动因素仍不确定。在这里,我们根据再分析和卫星观测,量化了中国不同生态系统(森林、灌丛、草地和农田)中植被光合作用对闪发性干旱的敏感性和响应幅度。通过采用极端梯度提升模型,我们还确定了影响这些闪发性干旱-光合作用关系的主要因素。我们表明,中国超过 51.46%的生态系统容易受到闪发性干旱的影响,而草原受到的抑制作用更为显著,表现在敏感性和响应幅度上(中值总初级生产力异常为-0.13)。我们进一步表明,背景气候差异(如年平均温度和干旱程度)主要调节了森林和灌丛的响应变化,较热/较冷或较干燥的生态系统受到闪发性干旱的抑制更为严重。然而,在草地和农田中,不同的植被响应归因于闪发性干旱期间异常水热气象条件的强度(如蒸气压亏缺(VPD)和温度异常)。闪发性干旱的影响随着 VPD 的增加而加剧,并与温度呈非单调关系,较冷或较热的温度会导致更严重的植被损失。我们的研究结果确定了易受闪发性干旱影响的脆弱生态区域,并使我们更好地了解植被对气候极端事件的光合作用响应,这可能有助于制定有效的管理策略。