Trees control soil moisture by drawing water through the roots and transpiring them to the air. They also lead to an opposite effect of reducing evaporation from the soil to the air by shading the ground and reducing the wind speed near the surface. Current watershed models simulate soil moisture at regional scales (tens to hundreds of km) and use extremely simplified representations of the interactions between vegetation and soil moisture. The differences between individual crowns and the effects of the canopy structure are not represented in these models. This project aims to improve understanding of the relationships between evaporation, transpiration and soil moisture in heterogeneous forest canopies, and how these relationships affect soil moisture heterogeneity from the tree scale to the ecosystem and regional scales. The project will capitalize on the existing wealth of data and on-going diverse observations at the University of Michigan Biological Station. A combination of detailed observations and state-of-the-art high-resolution modeling tools will be used. Novel radar-based volumetric observation of soil moisture, and in and above canopy micrometeorological measurements will be used, along with a novel integrated modeling approach.
The project will advance our capability to predict the effects of ecosystem structure at multiple scales on the exchanges of energy water and CO2 with the atmosphere, and on the functioning of the regional watershed. Such advancement is particularly important in conditions of changing climate and increased human disturbance to forests, which are expected to increase the spatial heterogeneity of forests and other important natural resources. It will also create a modeling tool that will have a truly transformative value in the hydrological and ecological sciences. Graduate students at Ohio State University and the University of Michigan will be supported through this collaborative project. Undergraduate students will be engaged in the proposed research. "Plant and Water", an educational K-12 community-outreach program will be developed to illustrate the underlying principles of water flow in soil-plant-atmosphere continuum and will train and employ undergraduate students as instructors at Big-Brothers Big-Sisters of Central Ohio Residental Camp Oty'Okwa, as part of the USDA Forest Service's "More Kids in the Woods" initiative, a program for underserved elementary-aged children within central Ohio.
