Climate change has substantially increased the frequency of extreme droughts in the Amazon basin, generating concern about impacts on the world's largest tropical forest, which contributes about one-seventh of the global vegetation carbon sink. Most research to understand drought impacts has focused on the immediate influences of such events, neglecting post-drought effects on ecosystems recovery. Since ecological processes are influenced by antecedent conditions, we analyzed whether extreme droughts affect vegetation growth (i.e., net primary productivity, NPP) recovery. Here, we evaluated the NPP in the Amazon basin from 2003 to 2020, a period in which drought frequency was almost double the decadal incidence of the last century. We show that NPP does respond to the coupled impacts of individual droughts and the post-drought impacts during ecosystem recovery. In particular, our results reveal that the ecosystems undergoing recovery show NPP about 13% lower than reference values based on the pre-drought state or in areas undisturbed by drought. NPP deficits have consistently increased with the extreme droughts of 2005, 2010, and 2015 due to the combined effects of disturbances magnitude and the length of recovery. If the expected increase in drought frequency and intensity does occur, reduced recovery may lead the Amazon Forest to an alternative ecosystem state with lower carbon uptake, contributing to a warming global climate.

中文翻译：

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抗旱债务导致亚马逊森林 NPP 下降

气候变化大大增加了亚马逊流域极端干旱的频率，引发了人们对世界上最大的热带森林的影响的担忧，该森林约占全球植被碳汇的七分之一。大多数了解干旱影响的研究都集中在此类事件的直接影响上，而忽略了干旱后对生态系统恢复的影响。由于生态过程受先行条件的影响，我们分析了极端干旱是否影响植被生长（即净初级生产力，NPP）的恢复。在这里，我们评估了 2003 年至 2020 年亚马逊流域的 NPP，在此期间，干旱频率几乎是上个世纪十年发生率的两倍。我们表明，NPP 确实对生态系统恢复过程中个别干旱和干旱后影响的耦合影响做出了反应。特别是，我们的结果表明，正在恢复的生态系统显示的 NPP 比基于干旱前状态或未受干旱干扰的地区的参考值低约 13%。由于干扰程度和恢复时间的综合影响，NPP 赤字随着 2005、2010 和 2015 年的极端干旱持续增加。如果预期的干旱频率和强度增加，恢复减少可能导致亚马逊森林进入碳吸收较低的替代生态系统状态，从而导致全球气候变暖。我们的结果表明，正在恢复的生态系统的 NPP 比基于干旱前状态或未受干旱干扰的地区的参考值低约 13%。由于干扰程度和恢复时间的综合影响，NPP 赤字随着 2005、2010 和 2015 年的极端干旱持续增加。如果预期的干旱频率和强度增加，恢复减少可能导致亚马逊森林进入碳吸收较低的替代生态系统状态，从而导致全球气候变暖。我们的结果表明，正在恢复的生态系统的 NPP 比基于干旱前状态或未受干旱干扰的地区的参考值低约 13%。由于干扰程度和恢复时间的综合影响，NPP 赤字随着 2005、2010 和 2015 年的极端干旱持续增加。如果预期的干旱频率和强度增加，恢复减少可能导致亚马逊森林进入碳吸收较低的替代生态系统状态，从而导致全球气候变暖。