Reduced transpiration response to precipitation pulses precedes mortality in a piñon-juniper woodland subject to prolonged drought.
Reduced transpiration response to precipitation pulses precedes mortality in a piñon-juniper woodland subject to prolonged drought.
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DOI：
10.1111/nph.12392
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发表时间：
2013-10
期刊：
影响因子：
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通讯作者：
J. Plaut;W. Duncan Wadsworth;R. Pangle;Enrico A. Yepez;Nathan G. McDowell;W. Pockman
中科院分区：
文献类型：
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作者：
J. Plaut;W. Duncan Wadsworth;R. Pangle;Enrico A. Yepez;Nathan G. McDowell;W. Pockman
据预测，全球气候变化将改变干旱的强度和持续时间，但降水模式变化对植被死亡率的影响难以预测。我们的目标是确定长期干旱或高于平均水平的降水是否会改变对驱动生产力和生存的单个降水脉冲的响应能力。利用蒸腾对事件大小、事件前土壤湿度和事件后蒸汽压亏缺的混合效应模型，对piñon-juniper （Pinus edulis-Juniperus monosperma）林地5年的降雨操纵实验数据进行了分析。重复处理包括灌溉、干旱、环境控制和基础设施控制。干旱条件下的死亡率最高，干旱树木死亡的脉冲后蒸腾减少可归因于超出干燥前条件的处理效果和事件规模的减小。特别是，死亡的树木对之前的浅层土壤湿度几乎没有反应，这表明浅层吸收根面积减少。灌溉树对降水脉冲的响应增强。长期的干旱引发了一个恶性循环，树木越来越无法利用脉冲土壤水分。因此，未来更频繁的干旱的叠加效应可能会增加与干旱有关的死亡率。
Global climate change is predicted to alter the intensity and duration of droughts, but the effects of changing precipitation patterns on vegetation mortality are difficult to predict. Our objective was to determine whether prolonged drought or above-average precipitation altered the capacity to respond to the individual precipitation pulses that drive productivity and survival. We analyzed 5 yr of data from a rainfall manipulation experiment in piñon-juniper (Pinus edulis-Juniperus monosperma) woodland using mixed effects models of transpiration response to event size, antecedent soil moisture, and post-event vapor pressure deficit. Replicated treatments included irrigation, drought, ambient control and infrastructure control. Mortality was highest under drought, and the reduced post-pulse transpiration in the droughted trees that died was attributable to treatment effects beyond drier antecedent conditions and reduced event size. In particular, trees that died were nearly unresponsive to antecedent shallow soil moisture, suggesting reduced shallow absorbing root area. Irrigated trees showed an enhanced response to precipitation pulses. Prolonged drought initiates a downward spiral whereby trees are increasingly unable to utilize pulsed soil moisture. Thus, the additive effects of future, more frequent droughts may increase drought-related mortality.