H056-0011
Using Wet-Dry Forest Extremes to Construct Water Budgets and Improve Watershed Modeling in Hardwood Forests of East Texas USA

Wednesday, 9 December 2020
Poster
Mairéad Mooney, Cedar Park, TX, United States, Peter V Caldwell, USDA Forest Svc, Coweeta Hydrologic Laboratory, Raleigh, NC, United States, Shulei Zhang, BNU Beijing Normal University, Beijing, China, Ajinkya G G Deshpande, Texas A&M University College Station, College Station, TX, United States, Christopher Adkison, Texas A&M University, Ecosystem Science and Management, College Station, TX, United States, Caitlyn Elizabeth Cooper, Texas A&M AgriLife Research, Vernon, TX, United States, Binayak Mohanty, Texas A&M University, Department of Biological and Agricultural Engineering, College Station, TX, United States, Gretchen R Miller, Texas A&M University College Station, Civil and Environmental Engineering, College Station, TX, United States, Mark Edward Everett, Texas A & M Univ, College Station, TX, United States, James K Brumbelow, Texas A&M University College Station, Civil & Environmental Engineering, College Station, TX, United States, Ashley Cross, Texas A&M University College Station, College Station, United States and Georgianne W Moore, Texas A&M University, Department of Ecosystem Science and Management, College Station, TX, United States
Abstract:
Eastern Texas is the driest extent of eastern deciduous forests, and these forests are highly impacted by land use and drought. Understanding the contributions of different forest types to the overall water budget of this ecologically sensitive region is key in developing accurate hydrological models intended to examine the role of land use on water quantity and quality. Here we calculated water budgets for a swampy bottomland hardwood forest site in the Texas Water Observatory and a dry post oak savannah site in the National Ecological Observatory Network (NEON) in the Lyndon B. Johnson (LBJ) National Grassland based on precipitation, soil moisture, and eddy-covariance evapotranspiration (ET) data collected at 30-minute intervals. To partition ET, transpiration (T) was calculated at each site using heat dissipation sapflow sensors installed in 11 blackjack (Quercus marilandica) and post oaks (Quercus stellata) at the Post Oak Savannah site and 16 southern live oak (Quercus virginiana), water oak (Quercus nigra), Shumard oak (Quercus shumardii), green ash (Fraxinus pennsylvanica), and Chinese tallow (Triadica sebifera) trees at the bottomland hardwood forest site.

Despite similar rainfall, the climate is warmer and more humid, and root zone soil moisture is much higher at the wet bottomland site with some periods of shallow groundwater compared to the dry savanna site. Although ET can account for the loss of nearly all precipitation from both these contrasting forest types, T was markedly higher at the wet bottomland site and comprises a greater portion of ET compared to the dry savanna site. A mechanistic understanding of groundwater recharge and runoff generation across these two contrasting forest types will aid in predicting changes in hydrology and inform forest management, conservation, and hydrologic model development in this rapidly urbanizing region.

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