Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China.
Jiangsu Provincial Key Laboratory of Geographic Information Science and Technology, International Institute for Earth System Sciences, Nanjing University, Nanjing, China; Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, Nanjing, China.
Sci Total Environ. 2019 Nov 25;693:133627. doi: 10.1016/j.scitotenv.2019.133627. Epub 2019 Jul 27.
Droughts and heatwaves have been and will continue to bring large risks to terrestrial ecosystems. However, the understanding of how plants respond to drought and heatwave over broad spatial scales is still limited. In this paper, we use the 2009/2010 drought in Yunnan and the 2013 heatwave over southern China as case studies to investigate the potential of using satellite-observed solar-induced chlorophyll fluorescence (SIF) to monitor vegetation responses to drought and heatwave over broad spatial scales. The 2009/2010 drought onset follows a strong soil moisture deficit due to the yearlong below-normal precipitation in Yunnan from the autumn of 2009 to the spring of 2010. In the summer of 2013, southern China experienced the strongest heatwave due to the sudden temperature increase and rainfall deficit. The results show that SIF can reasonably capture the spatial and temporal dynamics of drought and heatwave development, as indicated by the large reduction in fluorescence yield (SIF). Moreover, SIF demonstrates a significant reduction and earlier response than traditional vegetation indices (enhanced vegetation index, EVI) during the early stages of drought and heatwave events. For both study areas, the spatial and temporal correlation analysis demonstrates that the SIF anomalies are more sensitive to a high vapor pressure deficit (VPD) than low soil moisture. This study implies that satellite observations of SIF have great potential for accurate and timely monitoring of drought and heatwave developments.
干旱和热浪已经并将继续给陆地生态系统带来巨大风险。然而，对于植物如何在广泛的空间尺度上响应干旱和热浪，人们的理解仍然有限。在本文中，我们以 2009/2010 年云南干旱和 2013 年中国南方热浪为例，研究了利用卫星观测到的太阳诱导叶绿素荧光（SIF）来监测广泛空间尺度上植被对干旱和热浪响应的潜力。2009/2010 年干旱的发生是由于 2009 年秋季至 2010 年春季云南长达一年的降水低于正常水平，导致土壤水分严重不足。2013 年夏季，由于气温突然升高和降雨量不足，中国南方遭遇了最强热浪。结果表明，SIF 可以合理地捕捉干旱和热浪发展的时空动态，这表现为荧光产量（SIF）的大幅降低。此外，SIF 在干旱和热浪事件的早期阶段表现出比传统植被指数（增强型植被指数，EVI）更大的减少和更早的响应。对于这两个研究区域，时空相关分析表明，SIF 异常对高水汽压亏缺（VPD）比低土壤水分更为敏感。这项研究表明，卫星观测到的 SIF 具有准确、及时监测干旱和热浪发展的巨大潜力。
