Collaborative Research: Determining the role of hydraulic redistribution regimes in the critical zone - an experimental and modeling synthesis

协作研究：确定关键区域水力再分配机制的作用 - 实验和建模综合

• 批准号: 1417444
• 负责人: Praveen Kumar
• 金额: $ 22.84万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2014
• 资助国家: 美国
• 起止时间: 2014-08-01 至 2019-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1417444&HistoricalAwards=false
• 关键词: Collaborative; Research; Determining; role; hydraulic

Understanding and predicting interactions between aboveground and belowground ecohydrologic processes is challenging. Roots play an important role in linking aboveground plant ecophysiological processes, such as carbon, water, and energy exchange with the atmosphere, and the belowground processes associated with soil moisture and carbon, and microbial and nutrient dynamics. Interestingly, root water movement is not always unidirectional; plants create pathways for preferential water movement through a phenomenon called "hydraulic redistribution", by which water moves downward through the roots during wet periods but upward during drier periods. This project will study such hydraulic redistribution. The study will both provide insights for dryland regions and enable broader generalizations regarding the interaction between groundwater, roots, and aboveground assemblages and their role in whole-ecosystem performance. The salient aspect of this study is the coupling between field research and modeling to enable hypotheses testing and provide an upscaling framework from site-based studies. Given projections of a warmer climate, there has been a rapid expansion in scientific interest in how ecosystems will respond to periods of prolonged stress. This research will help address this critical issue.The scientific objective of the project is to systematically examine the role of hydraulic redistribution by roots as a mechanism for facilitating aboveground-belowground linkages that drive water and carbon dynamics, and the development of emergent spatial patterns of soil moisture and vegetation distribution. Field-based activities will be conducted at two sites in southern Arizona: a riparian site where precipitation inputs are augmented with belowground water sources and an upland site that lacks this secondary water pool. This research will advance the theory for understanding the interaction of aboveground and belowground ecohydrological processes using a model that mechanistically resolves the related processes. Coupled modeling and field experimentation and monitoring of root and stem sap flux, soil, carbon, whole-plant, and ecosystem-scale (via eddy covariance tower) water and carbon fluxes will mutually inform each other to provide detailed insights at a range of scales. Results from this study will be presented in kiosks on the tour route of Biosphere 2 that sees over 100,000 visitors per year that include K-12 students to retirees.

理解和预测地上和地下生态水文过程之间的相互作用具有挑战性。根在连接地上植物生态生理过程（例如与大气的碳、水和能量交换）以及与土壤水分和碳以及微生物和养分动态相关的地下过程方面发挥着重要作用。有趣的是，根部水分运动并不总是单向的；植物通过一种称为“水力再分配”的现象为水的优先运动创造通道，即水在潮湿时期通过根部向下移动，但在干燥时期向上移动。该项目将研究这种水力重新分配。该研究将为旱地地区提供见解，并就地下水、根系和地上组合之间的相互作用及其在整个生态系统性能中的作用提供更广泛的概括。这项研究的显着特点是现场研究和建模之间的耦合，以实现假设检验并提供基于现场研究的升级框架。鉴于气候变暖的预测，人们对生态系统如何应对长期压力的科学兴趣迅速扩大。这项研究将有助于解决这一关键问题。该项目的科学目标是系统地研究根系水力再分配的作用，作为促进地上地下联系的机制，从而驱动水和碳动态，以及新兴空间模式的发展土壤湿度和植被分布。实地活动将在亚利桑那州南部的两个地点进行：一个是通过地下水源增加降水输入的河岸地点，另一个是缺乏二次水池的高地地点。这项研究将使用机械地解决相关过程的模型来推进理解地上和地下生态水文过程相互作用的理论。对根和茎液流、土壤、碳、全植物和生态系统规模（通过涡流协方差塔）水和碳通量的耦合建模和现场实验以及监测将相互告知，以在一系列尺度上提供详细的见解。这项研究的结果将在生物圈 2 号旅游路线的信息亭中展示，该路线每年接待超过 100,000 名游客，其中包括 K-12 学生和退休人员。