School of Civil Engineering, Sun Yat-sen University, Guangzhou 510275, China.
The Pearl River Water Resources Research Institute, Guangzhou 510611, China.
J Environ Manage. 2024 Dec;371:122986. doi: 10.1016/j.jenvman.2024.122986. Epub 2024 Oct 30.
Climate change has triggered more frequent drought occurrence, which can have devastating impacts on the ecosystem functions. Studies on vegetation behavior during droughts have mainly focused on arid/semi-arid regions, yet the ecological and vegetation responses during drought in humid regions remain unclear. Here we systematically evaluated the evolution of the historic drought occurred in the humid Pearl River Basin in 2021 and quantified the vegetation responses using a multitude of vegetation indicators. Analyses showed that the East River Basin and North River Basin were the most severely hit by drought, which enhanced surface temperature and evapotranspiration, and caused soil moisture and terrestrial water storage deficits. Mean vegetation response time was shorter based on solar-induced fluorescence (SIF, 2.7 months) and the water use efficiency (WUE, 2.8 months), followed by the gross primary productivity (GPP, 3.2 months), and longer using the normalized difference vegetation index (NDVI, 4.2 months) and the vegetation optical depth (VOD, 5.0 months). By contrast, over 90% of the ecosystems recovered to their normal states within 3 months using all indicators. The results implied that the NDVI lacks sensitivity to changes in water stress in humid regions, and revealed that vegetation in humid regions may respond slowly and recover rapidly under droughts, which may relate to the water availability that enhances the resistance and resilience of the ecosystems.
气候变化引发了更频繁的干旱发生，这对生态系统功能造成了毁灭性的影响。关于干旱期间植被行为的研究主要集中在干旱/半干旱地区，但在湿润地区干旱期间的生态和植被响应仍不清楚。在这里，我们系统地评估了 2021 年发生在湿润的珠江流域的历史性干旱的演变，并使用多种植被指标量化了植被的响应。分析表明，东江流域和北江流域受干旱影响最为严重，干旱增强了地表温度和蒸散作用，导致土壤湿度和陆地水储量不足。基于太阳诱导荧光（SIF）的植被平均响应时间较短（2.7 个月），水利用效率（WUE）较短（2.8 个月），其次是总初级生产力（GPP）较短（3.2 个月），而归一化差异植被指数（NDVI）和植被光学深度（VOD）较长（4.2 个月）。相比之下，使用所有指标，超过 90%的生态系统在 3 个月内恢复到正常状态。结果表明，NDVI 对湿润地区水分胁迫变化缺乏敏感性，并揭示了湿润地区的植被在干旱条件下可能反应缓慢但恢复迅速，这可能与增强生态系统抵抗力和恢复力的水分供应有关。
