Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application, International Institute for Earth System Sciences, Nanjing University, Nanjing, Jiangsu 210023, China.
Yuxiu Postdoctoral Institute, Nanjing University, Nanjing, Jiangsu 210023, China.
Sci Adv. 2023 May 26;9(21):eabq4974. doi: 10.1126/sciadv.abq4974.
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.
亚马逊森林的光合作用和蒸散作用是全球碳和水循环的主要贡献者。然而，它们在区域尺度上的日变化模式及其对大气变暖与变干的响应仍不清楚，这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散作用代理来揭示出强烈的旱季下午光合作用（下降 6.7 ± 2.4%）和蒸散作用（下降 6.1 ± 3.1%）的抑制。光合作用在早晨对水汽压亏缺（VPD）呈正响应，但在下午呈负响应。此外，我们预测，在未来的旱季，该地区下午光合作用的抑制将被其早晨的增加所补偿。这些结果为亚马逊森林中气候与碳和水通量的复杂相互作用提供了新的认识，并为可能提高未来预测稳健性的初级生产力新出现的环境限制提供了证据。
