An ecohydrological perspective on drought‐induced forest mortality
An ecohydrological perspective on drought‐induced forest mortality
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DOI：
10.1002/2013jg002592
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发表时间：
2014-05
期刊：
影响因子：
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通讯作者：
A. Parolari;G. Katul;A. Porporato
中科院分区：
文献类型：
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作者：
A. Parolari;G. Katul;A. Porporato
由于降雨模式的变化，预计在未来的气候下，区域规模的干旱引起的森林死亡事件将变得更加频繁。这些死亡事件的发生是由外部因素，如干旱的频率和严重程度和内部因素，如树木的水分和碳的使用策略。为了探讨这些外源和内源因素之间的联系，森林死亡率，随机生态水文框架，占随机到达和干旱的长度，以及树木的水分和碳平衡土壤水分亏缺的响应。该系统的主要动力学的特点是相对于光谱的isohydroxy-isohydroxy气孔控制策略。使用控制干旱实验的结果，在碳饥饿和液压故障同时发生的点的最大可容忍的干旱长度进行预测，支持协调的液压功能和代谢的概念。我们发现在2002-2003年美国西南部干旱期间，在降水梯度上，模型预测和观察到的区域尺度冠层顶梢枯死之间存在定性一致性。模型和数据都表明，在降水阈值以下，死亡率迅速增加。该模型还提供了给定植物干旱策略和气候制度的死亡率频率的估计。拟议的生态水文学方法可以扩展到估计预期气候变化对干旱引起的森林死亡率的影响以及对水和碳平衡的相关后果。
Regional‐scale drought‐induced forest mortality events are projected to become more frequent under future climates due to changes in rainfall patterns. The occurrence of these mortality events is driven by exogenous factors such as frequency and severity of drought and endogenous factors such as tree water and carbon use strategies. To explore the link between these exogenous and endogenous factors underlying forest mortality, a stochastic ecohydrological framework that accounts for random arrival and length of droughts as well as responses of tree water and carbon balance to soil water deficit is proposed. The main dynamics of this system are characterized with respect to the spectrum of anisohydric‐isohydric stomatal control strategies. Using results from a controlled drought experiment, a maximum tolerable drought length at the point where carbon starvation and hydraulic failure occur simultaneously is predicted, supporting the notion of coordinated hydraulic function and metabolism. We find qualitative agreement between the model predictions and observed regional‐scale canopy dieback across a precipitation gradient during the 2002–2003 southwestern United States drought. Both the model and data suggest a rapid increase of mortality frequency below a precipitation threshold. The model also provides estimates of mortality frequency for given plant drought strategies and climate regimes. The proposed ecohydrological approach can be expanded to estimate the effect of anticipated climate change on drought‐induced forest mortality and associated consequences for the water and carbon balances.