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ARS Home » Pacific West Area » Tucson, Arizona » SWRC » Research » Research Project #431212

Research Project: Ecosystem Water and Carbon Cycling Across the Semiarid Western U.S.

Location: Southwest Watershed Research Center

Project Number: 2022-13610-012-12-S
Project Type: Non-Assistance Cooperative Agreement

Start Date: Sep 1, 2016
End Date: Aug 31, 2021

Over the last two decades, the eddy covariance technique has revolutionized our understanding of the exchanges of water and carbon between terrestrial ecosystems and atmosphere. Ecosystem flux datasets are increasingly more available and some have matured to the point that we can begin to understand interannual variability and trends in the fluxes. Now, there is a need for upscaling these site based measurements across the Long-term Agro-ecosystem Research (LTAR) network and other existing western U.S. ecosystem flux sites. Furthermore, there is a need to improve our understanding of how water limitation alters important ecosystem carbon cycle components like autotrophic and heterotrophic respiration and photosynthesis to improve our upscaling tools (models). The objectives of this project are to: 1) Conduct experiments to improve process level understanding of semiarid ecosystem carbon and water exchanges; 2) Incorporate improved understanding into earth system models; and 3) Conduct a regional scale western U.S. synthesis using a combination of models and flux tower data.

We will link field data collection to modeling at eddy covariance sites across the western U.S. Specifically, we will: 1. Conduct field experiments to quantify component-scale water and carbon fluxes at long-term flux tower locations within LTAR locations Walnut Gulch Experimental Watershed (WGEW) and Santa Rita Experimental Range (SRER). 2. Evaluate and improve earth system model representation of semiarid processes controlling water and carbon fluxes. 3. Take advantage of new long-term flux data ensembles from Fluxnet and new data from LTAR and NEON locations to conduct a flux data synthesis across the western U.S.