Forest sensitivity to a changing climate: Investigating the role of bedrock water storage

森林健康和溪水质量受到气候持续变化的威胁，气候变化导致积雪减少、干旱增加、树木枯死和河流干涸。深层地下(包括土壤下面的基岩)的作用已成为决定水的可获得性、从而决定森林和溪流命运的关键因素。然而，我们对地下生态系统何时、何地以及如何缓冲气候变化的理解知之甚少。这项研究计划的主要长期目标是量化气候和地下风化模式之间的相互作用如何调节水的储存和向植物和溪流的释放。这使我们能够更好地了解当今的蓄水动态以及在更温暖、更干燥的气候下的未来动态。短期目标是：(1)促进我们对冬季潮湿、夏季干旱气候(例如北美中部西海岸的气候)，包括雨雪过渡地区的季节性储水量对年降水量变化的敏感性的了解；以及(2)揭示植物生物群和径流对干旱的恢复能力的影响。这将通过对位于岩石类型、气候和构造历史的梯度上的野外观测站进行仪器测量来实现。我们将在相关空间尺度上监测生态水文过程，并开发可用于预测未来森林和河流状况和解释古记录的机制模型。我们预计，这项工作将使我们能够了解和预测植物依靠风化基岩中的水分储存来抵御干旱的情景，以及不断减少的积雪将如何影响夏季溪流中的低流量。我们的发现还将导致新的发展，并将深层地下水储存过程纳入地球系统模型，用于预测水和碳循环对气候变化的耦合响应。

Forest health and stream water quality are threatened by ongoing shifts in climate, which have resulted in decreased snowpack, increased drought, dead trees, and dry rivers. The role of the deep subsurface (including bedrock below the soil) has emerged as a key factor in determining water availability and therefore the fate of forests and streams. However, our understanding of when, where, and how the subsurface buffers ecosystems from climate shifts is poorly understood. The overarching, long-term goal of this research program is to quantify how the interaction between climate and subsurface weathering patterns regulates water storage and release to plants and streams. This enables us to better understand present-day water storage dynamics as well as future dynamics under a warmer, drier climate. The short-term objectives are to: (1) advance our understanding of seasonal water storage sensitivity to year-to-year precipitation variability in winter-wet, summer-dry climates in particular (e.g., those along the central west coast of North America), including rain-snow transition areas; and (2) reveal the consequences for plant biome and streamflow resilience to drought. This will be achieved by instrumenting field observatories located across gradients of rock type, climate, and tectonic history. We will monitor eco-hydrologic processes at relevant spatial scales and develop mechanistic models that can be used to predict future forest and stream states and interpret paleo-records. We anticipate that this work will enable us to understand and predict the scenarios in which plants rely on water storage in weathered bedrock to survive drought and how declining snowpacks will impact the magnitude of summer low flows in streams. Our findings will also result in the novel development and incorporation of deep subsurface water storage processes into Earth system models, which are used to predict the coupled response of the water and carbon cycles to a shifting climate.