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Groundwater-forest interactions during drought in temperate forests across scales

不同尺度温带森林干旱期间地下水与森林的相互作用

基本信息

批准号：
1700983
负责人：
Steven Loheide
金额：
$ 43.49万
依托单位：
University of Wisconsin-Madison
依托单位国家：
美国
项目类别：
Standard Grant
财政年份：
2017
资助国家：
美国
起止时间：
2017-08-01 至 2022-07-31
项目状态：
已结题

来源：
https://www.nsf.gov/awardsearch/showAward?AWD_ID=1700983&HistoricalAwards=false
关键词：
Groundwater forest interactions during drought

项目摘要

An estimated 3 trillion trees cover 42 million km2 worldwide - equivalent to the combined areas of North and South America. Societies around the globe rely on forests for water supply and provision of food, medicine, and forest products, as well as other recreational, cultural, and aesthetic benefits. Economically, tropical and temperate forests provide ecosystem goods and services totaling an estimated $23.32 trillion/yr worldwide. Drought - and changes in drought regimes - have the potential to disrupt this provisioning of forest services through reduced forest growth and increased vegetation stress and mortality. Groundwater, when and where available, may buffer specific portions of forest from the consequences of changing drought regimes. Strategies to adapt to drought impacts on forests requires improved understanding and forecasting of patterns, consequences, and feedbacks between drought response and groundwater. The overarching goal of this research is to evaluate groundwater as an ecosystem attribute that alleviates adverse impacts of changing drought regimes on temperate forests. This project will develop a suite of complementary drought detection tools to observe and link tree and forest response to drought, as influenced by groundwater. We will use simulation models to place our measurements in the context of a range of scenarios. This study will help society to better address forest and water resource challenges in the 21st century through dissemination of results to a broad array of stakeholders including researchers, forest and water resource managers, and the public. As drought regimes continue to change and impact forests, it is critical to identify and evaluate ecosystem attributes that alleviate drought stress and to develop novel methodologies to monitor drought response. Traditional methods rely on limited water stress observations of individual trees and stand level vegetation metrics derived from coarse resolution satellite images. Synthesis of such data dilutes species-specific responses and does not provide the necessary datasets to reveal mechanisms linking drought impacts on forests across spatial scales. Through the proposed work, multiple lines of evidence will be used to quantify species-specific tree and forest response to drought as buffered by groundwater. Specifically, this research proposes to investigate drought response across gradients of groundwater depth using: (1) tree ring chronologies to provide historic tree response and quantify the influence of groundwater on tree growth and drought vulnerability; (2) tree sway measurements from accelerometers to continuously monitor water stress and tree physiological response to drought; and, (3) hyperspectral remote sensing to spatially map species-specific foliar drought response. These novel methods for monitoring drought response will be aggregated with traditional complementary datasets to develop a suite of numerical models for simulating groundwater-tree interactions to mechanistically represent field observations. This project will provide a basis for understanding the role of groundwater in conferring drought resistance at the tree, transect, and landscape scales in temperate forests.

据估计，全世界有3万亿棵树，覆盖4200万平方公里，相当于南北美洲的面积总和。地球仪各地的社会都依赖森林来提供水源、食物、药品和森林产品，以及其他娱乐、文化和美学方面的好处。从经济上讲，热带和温带森林提供的生态系统产品和服务在全世界每年约为23.32万亿美元。干旱-以及干旱状况的变化-有可能通过减少森林生长、增加植被压力和死亡率，破坏森林服务的提供。地下水，在有地下水的情况下，可以缓冲森林的特定部分，使其不受变化中的干旱状况的影响。适应干旱对森林影响的战略需要更好地了解和预测干旱应对措施与地下水之间的模式、后果和反馈。这项研究的总体目标是评估地下水作为一种生态系统属性，说明不断变化的干旱制度对温带森林的不利影响。该项目将开发一套补充性干旱探测工具，以观察树木和森林对受地下水影响的干旱的反应，并将其联系起来。我们将使用模拟模型将我们的测量置于一系列场景的背景下。这项研究将通过向包括研究人员、森林和水资源管理人员以及公众在内的广泛利益攸关方传播研究结果，帮助社会更好地应对21世纪世纪的森林和水资源挑战。由于干旱状况不断变化并影响森林，因此必须确定和评估缓解干旱压力的生态系统属性，并制定新的方法来监测干旱应对措施。传统的方法依赖于有限的水胁迫观测的个别树木和林分水平的植被指标来自粗分辨率的卫星图像。这些数据的综合淡化了具体物种的反应，没有提供必要的数据集来揭示干旱对森林的影响在不同空间尺度上的联系机制。通过拟议的工作，将使用多条证据线来量化特定物种的树木和森林对地下水缓冲的干旱的反应。具体而言，本研究建议使用以下方法研究不同地下水深度梯度的干旱响应：（1）树木年轮年表，以提供历史树木响应，并量化地下水对树木生长和干旱脆弱性的影响;（2）树木摇摆的加速度计测量，以连续监测水分胁迫和树木对干旱的生理反应;（3）高光谱遥感在空间上绘制物种特异性叶片干旱响应。这些监测干旱响应的新方法将与传统的补充数据集汇总，以开发一套模拟地下水-树木相互作用的数值模型，从而从机械上代表实地观测。该项目将为了解地下水在温带森林树木、样带和景观尺度上赋予抗旱性的作用提供基础。