Collaborative Research: Forest Water Use and the Influence of Acid Deposition

合作研究：森林用水和酸沉积的影响

• 批准号: 1562019
• 负责人: Todd Scanlon
• 金额: $ 26.97万
• 依托单位: University of Virginia Main Campus
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-06-01 至 2021-05-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1562019&HistoricalAwards=false
• 关键词: Collaborative; Research; Forest; Water; Use

Forests sequester carbon dioxide from the atmosphere and take up water from soils, thus regulating the flow of water in streams. Some evidence suggests that the balance among these processes may have been fundamentally altered by high acid deposition ("acid rain") in the eastern United States during the post-Industrial Revolution period. During this period it is hypothesized that acid deposition decreased nutrients in the soil such as calcium, magnesium and potassium. This may have required trees to pump more water from the soil through their systems to obtain an adequate supply of nutrients, causing a subsequent loss of water flowing in streams. With the decline in acid deposition over the last 20-30 years, forests soils are able to retain more nutrients. This may reduce the amount of water that trees need to pump through their systems. Thus while maintaining the same rate of growth, trees may release less water to the atmosphere, improving their water use efficiency and leaving more water to feed into streams. This hypothesized response of forests to changing levels of acid deposition is not currently considered in the land surface components of global climate models. Since carbon dioxide and water vapor are the two most important greenhouse gases, it is vital to accurately model their land-atmosphere exchange. The proposed research uses a catchment-based approach to investigate the effects of changing acid deposition on forest water use efficiency. Tree ring carbon isotopes will be used to reconstruct historical forest water use efficiency time series within six catchments that have been differentially impacted by acid deposition due to distinctions between their underlying bedrock mineralogy and geological histories. The research will also capitalize on experimental treatments that have altered soil biogeochemistry in paired catchment designs (Bear Brook, ME; Hubbard Brook, NH; and Fernow Experimental Forest, WV). Stream discharge analysis and model-based approaches will be applied to detect the impact of acid deposition on forest water use efficiency and streamflow. The project will support a Ph.D. student, who will receive training in a wide range of field, laboratory, and modeling techniques, and at least eight undergraduate students. High school students will also be involved through established programs, and will participate in both field and lab activities. All senior members of the project team have track records of recruiting students from underrepresented groups. Results will be communicated to the broader scientific community through journal publications and conference presentations, and a special conference session will be organized with an objective of sharing research findings with the modeling community.

森林从大气中吸收二氧化碳，从土壤中吸收水分，从而调节溪流中的水流。一些证据表明，这些过程之间的平衡可能已被美国东部工业革命后时期的高酸沉降（“酸雨”）所根本改变。 在此期间，据推测，酸沉降减少了土壤中的养分，如钙，镁和钾。这可能需要树木从土壤中抽出更多的水通过它们的系统来获得足够的营养供应，从而导致河流中流动的水的损失。 随着过去20-30年酸沉降的减少，森林土壤能够保留更多的养分。这可能会减少树木需要通过其系统泵送的水量。因此，在保持相同的生长速度的同时，树木可以向大气中释放更少的水，提高它们的水利用效率，并留下更多的水流入河流。目前全球气候模型的陆地表面组成部分没有考虑森林对酸沉降水平变化的这种假设反应。由于二氧化碳和水蒸气是两种最重要的温室气体，因此精确模拟它们的陆地-大气交换至关重要。拟议的研究使用集水区为基础的方法来调查改变酸沉降对森林水分利用效率的影响。树轮碳同位素将被用来重建历史森林水分利用效率的时间序列内的六个集水区，已受到不同的影响，由于其潜在的基岩矿物和地质历史之间的区别酸沉积。该研究还将利用在成对集水区设计（Bear Brook，ME; Hubbard Brook，NH;和Fernow Experimental Forest，WV）中改变土壤地球化学的实验处理。河流流量分析和基于模型的方法将被应用于检测酸沉降对森林水利用效率和径流的影响。该项目将支持一个博士学位。学生，谁将接受培训，在广泛的领域，实验室和建模技术，和至少八名本科生。高中学生也将通过既定的计划参与，并将参加实地和实验室活动。项目团队的所有高级成员都有从代表性不足的群体中招募学生的记录。研究结果将通过期刊出版物和会议报告传达给更广泛的科学界，并将组织一次特别会议，目的是与建模界分享研究成果。