Ecohydrologic Dynamics of Rock Moisture in a Montane Catchment of the Colorado Front Range
Ecohydrologic Dynamics of Rock Moisture in a Montane Catchment of the Colorado Front Range
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DOI：
10.1029/2022wr034117
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发表时间：
2023-06
影响因子：
5.4
通讯作者：
E. Burns;D. Rempe;A. Parsekian;L. Schmidt;K. Singha;H. Barnard
中科院分区：
文献类型：
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作者：
E. Burns;D. Rempe;A. Parsekian;L. Schmidt;K. Singha;H. Barnard
美国西部的变暖继续减少积雪，延长生长季节，增加大气需求，导致山地森林水分可用性的不确定性。由于许多高地森林土壤较薄，并且广泛扎根于风化的基岩中，因此深层渗透带的水可能是植被的重要晚季水源，可以缓解森林的水分压力。理解深层渗透带作为水库的作用的一个关键障碍是量化植物在那里持有的可用水。我们量化了落基山脉山区集水区深层渗透区岩石水分的时空动态。岩石水分的直接测量伴随着降水、蒸腾、土壤水分、叶片水势和地下水的监测。通过重复核磁共振和中子探针测量，我们发现所有监测地块的岩石水分都在枯竭。生长季岩石水分耗竭的幅度反映了地表上植被密度和蒸腾作用，耗竭的岩石水分发生在地表以下0.3 ~ 5 m。对储水量的估计表明，风化岩石储水量至少占年平均降水量的4%-12%。持续的蒸腾作用以及估算的土壤基质电位和叶片水势之间的差异表明，岩石水分可能减轻干旱胁迫。这些发现为落基山脉的岩石水分利用提供了一些初步的测量结果，并表明岩石水分的利用不仅仅局限于干旱或地中海气候时期。
Warming across the western United States continues to reduce snowpack, lengthen growing seasons, and increase atmospheric demand, leading to uncertainty about moisture availability in montane forests. As many upland forests have thin soils and extensive rooting into weathered bedrock, deep vadose‐zone water may be a critical late‐season water source for vegetation and mitigate forest water stress. A key impediment to understanding the role of the deep vadose zone as a reservoir is quantifying the plant‐available water held there. We quantify the spatiotemporal dynamics of rock moisture held in the deep vadose zone in a montane catchment of the Rocky Mountains. Direct measurements of rock moisture were accompanied by monitoring of precipitation, transpiration, soil moisture, leaf‐water potentials, and groundwater. Using repeat nuclear magnetic resonance and neutron‐probe measurements, we found depletion of rock moisture among all our monitored plots. The magnitude of growing season depletion in rock moisture mirrored above‐ground vegetation density and transpiration, and depleted rock moisture was from ∼0.3 to 5 m below ground surface. Estimates of storage indicated weathered rock stored at least 4%–12% of mean annual precipitation. Persistent transpiration and discrepancies between estimated soil matric potentials and leaf‐water potentials suggest rock moisture may mitigate drought stress. These findings provide some of the first measurements of rock moisture use in the Rocky Mountains and indicated rock moisture use is not just confined to periods of drought or Mediterranean climates.