• There is a consensus about negative impacts of droughts in Amazonia. Yet, extreme wet episodes, which are becoming as severe and frequent as droughts, are overlooked and their impacts remain poorly understood. Moreover, drought reports are mostly based on forests over a deep water table (DWT), which may be particularly sensitive to dry conditions.
• Based on demographic responses of 30 abundant tree species over the past two decades, in this study we analyzed the impacts of severe droughts but also of concurrent extreme wet periods, and how topographic affiliation (to shallow ‐ SWTs ‐ or deep ‐ DWTs ‐ water tables), together with species functional traits, mediated climate effects on trees.
• Dry and wet extremes decreased growth and increased tree mortality, but interactions of these climatic anomalies had the highest and most positive impact, mitigating the simple negative effects. Despite being more drought‐tolerant, species in DWT forests were more negatively affected than hydraulically vulnerable species in SWT forests.
• Interaction of wet–dry extremes and SWT depth modulated tree responses to climate, providing buffers to droughts in Amazonia. As extreme wet periods are projected to increase and at least 36% of the Amazon comprises SWT forests, our results highlight the importance of considering these factors in order to improve our knowledge about forest resilience to climate change.

中文翻译：

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干旱的另一面：极端湿气和地形是亚马逊森林负面干旱影响的缓冲

• 人们对亚马逊地区干旱的负面影响达成了共识。然而，极端干旱事件的发生和干旱与干旱一样频繁而被忽视，其影响仍然知之甚少。此外，干旱报告主要基于深水位（DWT）上的森林，这可能对干旱条件特别敏感。
• 根据过去20年中30种丰富的树种的人口统计学响应，在本研究中，我们分析了严重干旱的影响以及同时发生的极端潮湿时期的影响，以及地形的隶属关系（浅层SWT或深层DWT地下水位） ），以及物种的功能性状，对树木介导的气候影响。
• 极端干旱和极端潮湿会降低生长并增加树木死亡率，但是这些气候异常的相互作用具有最大和最积极的影响，从而减轻了简单的负面影响。尽管更耐旱，但DWT森林中的物种比SWT森林中的水力脆弱物种受到的负面影响更大。
• 干湿极端和SWT深度调制的树木对气候响应的相互作用，为亚马逊地区的干旱提供了缓冲。由于预计极端潮湿期将增加，并且至少36％的亚马逊河流域包括SWT森林，因此我们的结果强调了考虑这些因素的重要性，以提高我们对森林对气候变化的适应力的知识。