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; 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.

连续美国，一半以上的淡水供应起源于森林流域。因此，至关重要的是，要正确管理森林的浅水集水区，以确保为水生生态系统和下游社区提供清洁和充足的供水。对森林实验流域的研究确定，减少森林覆盖率通常会增加水产量，而造林会降低水产量。但是，仍然没有关于流量变化的幅度和持久性的一致性，尤其是在最高和最低流量的时期。这是因为森林收获或其他森林干扰与流量之间的联系本质上是一个“黑匣子”，从而不了解影响水流的机制。这项研究将通过研究当代森林管理如何影响良好的加利福尼亚沿海水域中的水运动和存储，从而扩大我们基于过程的理解。这项研究的结果将提供证据，以激发沿海流域的新森林管理，并提高人们对植被与供水之间联系的基础知识。这些结果将与USDA森林服务局和加利福尼亚林业和消防部门结合产生，这将利用结果来更新加利福尼亚的森林实践规则。提高我们对森林干扰如何影响水的存储和释放水的定量理解越来越重要。但是，尚不清楚干扰如何影响除了年水平以外的时间尺度上的水分室化。这是因为只能在配对的流域研究中推断出流量增加的机制，这是量化森林干扰水文效应的最流行工具。合并的质量平衡和双水同位素方法提供了潜力，可以批判性地提高我们对干扰对驱动水存储和释放的过程和机制的影响的理解。在这里，假设森林流域的生态水文反应与干扰的严重程度成正比。使用不同强度的森林收获（0％，35％，55％和75％去除治疗植被）作为研究森林干扰的机制，将解决以下研究问题：增加的干扰水平会影响不同山坡位置的水预算水平？森林干扰如何影响土壤，地下水，溪流和树木之间的水分离？为了回答这些问题，这项研究采用了一种新颖的方法来连接森林干扰影响水预算，地下水运动和植物用水的过程，通过结合质量平衡分析和双水同位素。水预算的所有组成部分（即水流，土壤水分，地下水，蒸散液和雾）将被监测，并与双重稳定的同位素（2H和18O）一起监测并结合使用。这项研究还涉及对基于现场的水文研究的关键呼吁，以告知水文模型，以回答有关干扰对水资源的影响的关键问题。该奖项反映了NSF的法定任务，并被认为是值得通过基金会的知识分子和更广泛影响的评估评估的评估值得支持的。