CAREER: Understanding the importance of biomass hydraulic capacitance for transpiration

森林在水循环和碳循环之间提供了重要的联系。全球气温上升和干旱的可能性威胁着森林生态系统。由于土壤和大气中的水分有限，干旱会限制树木循环碳和水的能力。像许多计划一样，树木将水分从土壤转移到根部，通过树干和树枝向上，并通过叶子进入大气。它们可以移动和储存大量的水，这些水在维持植物功能和防止干旱胁迫方面起着关键作用。较大的树木通常具有更大的储水量，保护它们免受土壤水分压力。本研究评估了森林储水在温带和半干旱森林中树木如何应对水供需压力中的作用。这项工作将开发一种新的传感器来测量树木的水分含量，并生成一个广泛的活的、成熟的树木的水分含量数据集，这将促进对不同树木如何获取、储存和利用水分的了解。它将进一步开发计算机模型来模拟森林储水对水和碳循环的影响，并应用新的卫星数据分析来评估水的驻留地点，并预测干旱、树木死亡和森林火灾的可能性。将以英语和西班牙语开发不同森林的互动式虚拟实地考察，以增加实地经验和扩大地球科学的多样性。这项研究的中心目标是增加对树木中水储存和利用的物理学的理解。这种对电容的新理解将用于开发植物水力学模型，并将基于个体的生物质储水地面测量与区域和全球尺度的遥感数据产品联系起来，用于模型评估，以及生成生态系统压力的预测。这项研究工作将结合现场观测和仪器开发与模型开发和评估。生物量储水量、水势和汁液通量的测量将用于创建基于个体的植物水力学模型，该模型能够再现干旱后再湿润的电容性反应。这些数据还将使用统计标度算法对区域尺度遥感生物量含水量进行实地调查。最后，这项工作将提供一条途径，将含水量的遥感观测纳入区域尺度上具有植物水力能力的陆地-大气模型。该研究将揭示生物质储水在控制植被蒸腾对VPD和土壤水分胁迫的响应中的作用，并将增强我们在多尺度上模拟植被对干旱胁迫和干旱恢复的响应的能力。在这些研究活动的同时，将创建交互式数字实地考察，让高中和大学水平的学生沉浸在科学团队中，以了解更多关于不同森林类型的碳、水和能量循环的知识。该奖项反映了美国国家科学基金会的法定使命，并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，被认为值得支持。

Forests provide an important link between the water cycle and the carbon cycle. Increasing global temperature and chances of drought threaten the forest ecosystems. Droughts can limit the ability of trees to cycle carbon and water due to limited amount of water in the soil and atmosphere. Like many plans, trees move water from the soil into the roots, up through trunks and branches, and out through the leaves into the atmosphere. They can move and store large amounts of water that play a key role on maintaining plant functions and prevent drought stress. Bigger trees typically have larger volumes of water storage, protecting them from soil water stress. This study assesses the role of forest water storage in how trees respond to water supply and demand stresses in a temperate and a semi-arid forest. The work will develop a new sensor to measure water content in trees and generate an extensive dataset of water content in living, mature trees that will advance knowledge on how different trees acquire, store, and use water. It will further develop computer models to simulate the effects of forest water storage on the water and carbon cycles and apply new satellite data analysis to assess where the water is residing and predict the likelihood of droughts, tree mortality, and forest fires. An interactive virtual field trip of different forests will be developed, both in English and Spanish, to increase access to field experience and expand diversity in the Earth sciences. The central goal of this research is to increase understanding of the physics of water storage and use in trees. This novel understanding of capacitance will be used to develop plant hydraulics models and to connect individual-based ground measurements of biomass water storage to remotely sensed data products at regional and global scales for use in model evaluation, as well as to generate predictions of ecosystem stress. This research effort will couple field-based observations and instrumentation development with model development and evaluation. Measurements of biomass water storage, water potential, and sap flux will be used to create individual-based plant hydraulics models capable of reproducing the capacitive response to rewetting after drought. These data will also be used to ground truth regional-scale remotely sensed biomass water content using a statistical scaling algorithm. Finally, this work will provide a pathway to incorporate remote sensing observations of water content into plant hydraulics-capable land-atmosphere models at the regional scale. This research will shed new light on the role biomass water storage plays in governing transpiration response to VPD and soil water stresses and will enhance our ability to model vegetation responses to both drought stress and drought recovery at multiple scales. Simultaneously to these research activities, interactive digital field trips will be created to allow students at high school and college levels to immerse themselves with the scientific team to learn more about carbon, water, and energy cycling in different forest types.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.