Photosynthesis and evapotranspiration in Amazonian forests are major contributors to the global carbon and water cycles. However, their diurnal patterns and responses to atmospheric warming and drying at regional scale remain unclear, hindering the understanding of global carbon and water cycles. Here, we used proxies of photosynthesis and evapotranspiration from the International Space Station to reveal a strong depression of dry season afternoon photosynthesis (by 6.7 ± 2.4%) and evapotranspiration (by 6.1 ± 3.1%). Photosynthesis positively responds to vapor pressure deficit (VPD) in the morning, but negatively in the afternoon. Furthermore, we projected that the regionally depressed afternoon photosynthesis will be compensated by their increases in the morning in future dry seasons. These results shed new light on the complex interplay of climate with carbon and water fluxes in Amazonian forests and provide evidence on the emerging environmental constraints of primary productivity that may improve the robustness of future projections.

中文翻译：

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巨大的昼夜补偿效应减轻了亚马逊森林对大气变暖和干燥的反应

亚马逊森林中的光合作用和蒸发蒸腾作用是全球碳循环和水循环的主要贡献者。然而，它们的昼夜模式和对区域尺度大气变暖和干燥的反应仍不清楚，阻碍了对全球碳和水循环的理解。在这里，我们使用国际空间站的光合作用和蒸发蒸腾代理来揭示旱季下午光合作用（6.7 ± 2.4%）和蒸发蒸腾（6.1 ± 3.1%）的强烈抑制。光合作用在早上对水蒸气压不足 (VPD) 有积极反应，但在下午则有消极反应。此外，我们预计，在未来的旱季，区域性下午的光合作用将被早晨的增加所补偿。