Gross primary productivity (GPP) is the largest flux in the global terrestrial carbon cycle. Drought has significantly impacted global terrestrial GPP in recent decades, and has been projected to occur with increasing frequency and intensity. However, the drought risk of global terrestrial GPP has not been well investigated. In this study, global terrestrial GPP during 1981–2016 was simulated with the process-based Boreal Ecosystem Productivity Simulator model. Then, the drought risk of GPP was quantified as the product of drought probability and reduction of GPP caused by drought, which was determined using the standardized precipitation evapotranspiration index. During the study period, the drought risk of GPP was high in the southeastern United States, most of South America, southern Europe, central and eastern Africa, eastern and southeastern Asia, and eastern Australia. It was low at some high latitudes of the Northern Hemisphere and in part of tropical South America, where terrestrial GPP increased slightly in drought years. The drought risk of terrestrial GPP was greater during 2000–2016 than during 1981–1999 in 21 out of 24 climatic zones. The global mean drought risk of GPP increased from 13.6 g C m⁻² yr⁻¹ during 1981–1999 to 19.3 g C m⁻² yr⁻¹ during 2000–2016. The increase in drought risk of GPP was mainly caused by the increase in drought vulnerability. Simulation experiments indicated that the drought vulnerability of GPP was mainly induced by climatic variability. This study advances our understanding on the impact of drought on GPP over the globe.

中文翻译：

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遥感驱动过程模型检测过去 40 年全球陆地总初级生产力的干旱风险

总初级生产力 (GPP) 是全球陆地碳循环中最大的通量。近几十年来，干旱对全球陆地 GPP 产生了重大影响，并且预计会以越来越多的频率和强度发生。然而，全球陆地 GPP 的干旱风险尚未得到很好的研究。在这项研究中，1981-2016 年期间的全球陆地 GPP 使用基于过程的北方生态系统生产力模拟器模型进行了模拟。然后，将GPP的干旱风险量化为干旱概率与干旱引起的GPP减少的乘积，使用标准化降水蒸散指数确定。研究期间，美国东南部、南美洲大部、欧洲南部、非洲中东部、东亚和东南亚以及澳大利亚东部。它在北半球的一些高纬度地区和南美洲的部分热带地区较低，在干旱年份陆地 GPP 略有增加。在 24 个气候带中的 21 个，2000-2016 年期间陆地 GPP 的干旱风险高于 1981-1999 年期间。GPP 的全球平均干旱风险从 13.6 g C m 增加^-2  yr ^-1 1981-1999 年至 19.3 g C m ^-2  yr ^-1 2000-2016 年。GPP干旱风险的增加主要是由于干旱脆弱性的增加。模拟实验表明，GPP 的干旱脆弱性主要是由气候变异引起的。这项研究增进了我们对干旱对全球 GPP 影响的理解。