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首页> 外文期刊>Water >Canopy Transpiration and Stomatal Responses to Prolonged Drought by a Dominant Desert Species in Central Asia
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Canopy Transpiration and Stomatal Responses to Prolonged Drought by a Dominant Desert Species in Central Asia

机译：中亚主要荒漠物种对长期干旱的冠层蒸腾作用和气孔响应

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摘要

In arid and semiarid lands, canopy transpiration and its dynamics depend largely on stomatal sensitivity to drought. In this study, the sap flow of a dominant species, Haloxylon ammodendron growing in Central Asian deserts, was monitored using Granier-type sensors, from which the canopy stomatal conductance was derived. The responses of canopy transpiration and stomatal conductance to environmental variables during the second half of the growing season, when annual prolonged drought occurred, was analyzed for four continuous years, from 2013 to 2016. A soil water content (SWC) of 3% was identified as the lower soil water threshold for this species, below which the plant lost the ability for stomatal regulation on water loss and suffered the risk of mortality. Above this threshold, the sensitivity of canopy transpiration to vapor pressure deficit, VPD (K), was linearly correlated with SWC, which mainly resulted from different stomatal behaviors at varying drought intensities. Stomatal sensitivity to VPD (m/G sref ) increased linearly with soil moisture deficit, inducing a shift from more anisohydric to a more isohydric stomatal behavior. The flexibility of stomatal behavior regarding soil drought was one key element facilitating the survival of H. ammodendron in such an extreme dry environment.
机译：在干旱和半干旱地区，冠层蒸腾作用及其动态很大程度上取决于气孔对干旱的敏感性。在这项研究中，使用格兰尼尔（Granier）型传感器监测了在中亚沙漠中生长的优势种梭梭梭的汁液流动，由此得出了冠层气孔导度。从2013年至2016年连续四年分析了生长季节下半年（每年发生长期干旱）期间冠层蒸腾和气孔导度对环境变量的响应。确定土壤水分含量（SWC）为3％作为该物种较低的土壤水阈值，低于该阈值，植物将失去气孔调节水分流失的能力，并面临死亡的风险。高于此阈值，冠层蒸腾对蒸气压亏缺的敏感性VPD（K）与SWC线性相关，这主要是由于干旱强度不同而气孔行为不同所致。气孔对VPD的敏感性（m / G sref）随着土壤水分亏缺而线性增加，导致气孔行为从更多的无水状态转变为更多的等水度行为。在这种极端干燥的环境中，气孔行为对土壤干旱的灵活性是促进双歧杆菌存活的关键因素之一。

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