2005 Annual Report 4d.Progress report. This report serves to document research conducted under a specific cooperative agreement between ARS and Texas A&M University, Texas Agricultural Experiment Station (TAES) at Temple, TX, that was initiated during the last year. Additional details of research can be found in the report from the parent project 6206-11220-004-00D Global Change and the Carbon Balance on Western Rangelands. A consortium of ARS scientists and cooperators from western U.S. sites (Burns, OR; Dubois, ID; Ft. Collins, CO; Cheyenne, WY; Las Cruces, NM; Mandan, ND; Miles City, MT; Temple, TX; Tucson, AZ; and El Reno and Woodward, OK) has for 7 or more years been measuring carbon dioxide (CO2) fluxes over a variety of rangeland types using identical instrumentation. New sites, using eddy covariance (EC) instrumentation, were added at State College, Pennsylvania, and El Reno, Oklahoma, during the last 3 years. During the last year, TAES cooperators in Temple continued to conduct quality control of flux data; summarize, share, and archive quality-controlled network data; troubleshoot (via email and telephone) problems with the operation of instrumentation for measuring fluxes and environmental data; loan instrumentation to other locations; coordinate yearly calibration of net radiometers; and assist in operation of eddy covariance instrumentation at El Reno, Oklahoma, and University Park, Pennsylvania. Cooperators also were responsible for analyzing and providing continuous, real time quality control of flux data collected in Las Cruces, NM.