The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence
The role of ecosystem transpiration in creating alternate moisture regimes by influencing atmospheric moisture convergence
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DOI：
10.1111/gcb.16644
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发表时间：
2022-05
影响因子：
11.6
通讯作者：
A. Makarieva;A. Nefiodov;A. Nobre;M. Baudena;U. Bardi;D. Sheil;S. Saleska;R. D. Molina;A. Rammig
中科院分区：
文献类型：
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作者：
A. Makarieva;A. Nefiodov;A. Nobre;M. Baudena;U. Bardi;D. Sheil;S. Saleska;R. D. Molina;A. Rammig
陆地水循环通过四种通量将土壤和大气水分库联系起来：降水、蒸发、径流和大气水分辐合（水汽净输入以平衡径流）。这些过程中的每一个都对维持人类和生态系统的福祉至关重要。预测水循环如何对植被覆盖的变化作出反应仍然是一个挑战。最近，亚马逊流域植物蒸腾作用的变化与降雨量的变化不成比例地相关，这表明即使是蒸腾作用的微小下降（例如，森林砍伐）将导致更大的降雨量下降。在这里，约束这些研究结果的质量守恒定律，我们表明，在一个足够潮湿的大气中，森林蒸腾作用可以控制大气水分收敛，增加蒸腾作用增强大气水分进口和结果在水产量。相反，在足够干燥的大气中，蒸腾作用的增加减少了大气水分的收敛和水分的产生。这种以前未被认识到的二分法可以解释水量如何响应于再绿化的混合观察，正如我们从中国黄土高原的例子中所说明的那样。我们的分析表明，任何额外的降水再循环，由于额外的植被增加降水，但减少当地的产水量和稳态径流。因此，在干旱地区/时期和生态恢复的早期阶段，植被的作用可以局限于降水再循环，而一旦达到较湿润的阶段，额外的植被会增强大气水分的收敛和水分的产量。最近的分析表明，后一种制度主导了陆地水循环对重新绿化的全球反应。评估制度之间的过渡，并认识到植被的潜力，以提高水分收敛，是至关重要的特点砍伐森林的后果，以及激励和指导生态恢复。
The terrestrial water cycle links the soil and atmosphere moisture reservoirs through four fluxes: precipitation, evaporation, runoff, and atmospheric moisture convergence (net import of water vapor to balance runoff). Each of these processes is essential for sustaining human and ecosystem well‐being. Predicting how the water cycle responds to changes in vegetation cover remains a challenge. Recently, changes in plant transpiration across the Amazon basin were shown to be associated disproportionately with changes in rainfall, suggesting that even small declines in transpiration (e.g., from deforestation) would lead to much larger declines in rainfall. Here, constraining these findings by the law of mass conservation, we show that in a sufficiently wet atmosphere, forest transpiration can control atmospheric moisture convergence such that increased transpiration enhances atmospheric moisture import and results in water yield. Conversely, in a sufficiently dry atmosphere increased transpiration reduces atmospheric moisture convergence and water yield. This previously unrecognized dichotomy can explain the otherwise mixed observations of how water yield responds to re‐greening, as we illustrate with examples from China's Loess Plateau. Our analysis indicates that any additional precipitation recycling due to additional vegetation increases precipitation but decreases local water yield and steady‐state runoff. Therefore, in the drier regions/periods and early stages of ecological restoration, the role of vegetation can be confined to precipitation recycling, while once a wetter stage is achieved, additional vegetation enhances atmospheric moisture convergence and water yield. Recent analyses indicate that the latter regime dominates the global response of the terrestrial water cycle to re‐greening. Evaluating the transition between regimes, and recognizing the potential of vegetation for enhancing moisture convergence, are crucial for characterizing the consequences of deforestation as well as for motivating and guiding ecological restoration.