Collaborative Research: Water partitioning between trees, soils, and streams following forest disturbance

合作研究：森林干扰后树木、土壤和溪流之间的水分配

• 批准号: 1807165
• 负责人: Salli Dymond
• 金额: $ 4.31万
• 依托单位: University of Minnesota Duluth
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2018
• 资助国家: 美国
• 起止时间: 2018-07-15 至 2020-09-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1807165&HistoricalAwards=false
• 关键词: Collaborative; Research; Water; partitioning; between

Over half of the freshwater supply in the contiguous United States originates in forested watersheds. It is thus critical that forested headwater catchments are properly managed to ensure clean and ample water supplies for aquatic ecosystems and downstream communities. Research on forested experimental watersheds has established that reducing forest cover generally increases water yield and that afforestation decreases water yield. However, there is still not agreement on the magnitude and persistence of changes in streamflow, particularly during periods of the highest and lowest streamflow. This is because the connection between forest harvesting, or other forest disturbances, and streamflow is essentially a "black box", whereby the mechanisms influencing streamflow are not understood. This research will broaden our process-based understanding of forest hydrology by investigating how contemporary forest management affects water movement and storage in a well-studied coastal California watershed. Results of this research will provide evidence to motivate new forest management in coastal watersheds and lead to better foundational knowledge of the linkages between vegetation and water supply. These results will be generated in conjunction with the USDA Forest Service and the California Department of Forestry and Fire Protection, which will use the results to update California's Forest Practice Rules. It is increasingly critical to improve our quantitative understanding of how forest disturbances affect the storage and release of water through catchments. However, it is not yet understood how disturbances impact water compartmentalization at time scales other than the annual water balance. This is because the mechanisms by which streamflow increases can only be inferred in paired watershed studies, which have been the most popular tool for quantifying hydrological effects of forest disturbance. A combined mass balance and dual water isotope approach offers the potential to critically improve our understanding of the effects of disturbances on the processes and mechanisms that drive water storage and release. Here, it is hypothesized that the ecohydrological response of a forested watershed is proportional to the severity of disturbance. Using different intensities of forest harvesting (0%, 35%, 55%, and 75% removal of pre-treatment vegetation) as a mechanism for studying forest disturbances, the following research questions will be addressed: How do increasing levels of disturbance affect the water budget at different hillslope positions? How does forest disturbance affect the separation of water between soils, groundwater, streams, and trees? To answer these questions, this study takes a novel approach to connect the processes by which forest disturbance affects water budgets, subsurface water movement, and plant water use by combining a mass balance analysis and dual water isotopes. All components of the water budget (i.e., streamflow, soil moisture, groundwater, evapotranspiration, and fog) will be monitored and coupled with dual stable isotopes (2H and 18O). This study also addresses critical calls for field-based hydrologic research to inform hydrologic models to answer key questions about disturbance impacts on water resources.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

在美国本土，超过一半的淡水供应来自森林流域。因此，必须妥善管理森林覆盖的水源集水区，以确保为水生生态系统和下游社区提供清洁和充足的水。对森林实验流域的研究表明，减少森林覆盖通常会增加水量，而植树造林会减少水量。然而，对于流量变化的幅度和持续性，特别是在流量最高和最低的时期，仍然没有达成一致意见。这是因为森林采伐或其他森林干扰与径流之间的联系本质上是一个“黑匣子”，影响径流的机制尚不清楚。这项研究将扩大我们的森林水文过程为基础的理解，通过调查当代森林管理如何影响水的运动和存储在一个研究良好的沿海加州流域。这项研究的结果将提供证据，以激励新的森林管理在沿海流域，并导致更好的基础知识之间的联系植被和供水。这些结果将与美国农业部林务局和加州林业和消防部一起产生，后者将使用这些结果来更新加州的森林实践规则。这是越来越重要的，以提高我们的定量了解森林干扰如何影响储存和释放的水通过集水区。然而，目前还不清楚扰动如何影响水的划分在时间尺度以外的年度水平衡。这是因为径流量增加的机制只能在成对的流域研究中推断，这是最流行的工具，用于量化森林干扰的水文影响。结合质量平衡和双重水同位素的方法提供了一个潜在的关键提高我们的理解的影响，驱动水的储存和释放的过程和机制的干扰。在这里，它是假设的生态水文响应的森林流域是成比例的干扰的严重程度。使用不同强度的森林采伐（0%，35%，55%和75%去除预处理植被）作为研究森林干扰的机制，将解决以下研究问题：如何增加干扰水平影响在不同的山坡位置的水预算？森林干扰如何影响土壤、地下水、溪流和树木之间的水分分离？为了回答这些问题，本研究采取了一种新的方法来连接森林干扰影响水收支，地下水运动，植物水分利用相结合的质量平衡分析和双水同位素的过程。水预算的所有组成部分（即，将监测河流流量、土壤湿度、地下水、蒸散量和雾），并与双稳定同位素（2H和18O）相结合。这项研究还解决了基于实地的水文研究的关键要求，为水文模型提供信息，以回答有关干扰对水资源影响的关键问题。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。