CAREER: Understanding the importance of biomass hydraulic capacitance for transpiration

点击翻译按钮获取中文摘要

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.