PGSVALID2

Accurate prediction of the regional responses of CO2 flux to changing climate, land use, and management requires models that are parameterized and tested against measurements made in multiple land cover types and over seasonal to inter-annual time scales. Models predicting fluxes for un-irrigated agriculture were posed with the challenge of characterizing the onset and severity of plant water stress. We conducted a study that quantified the spatial heterogeneity and temporal variations in land surface-atmosphere exchanges of CO2, water, and energy. Eddy covariance flux measurements were made in pastures and dominant crop types surrounding the US-DOE Atmospheric Radiation Measurement Program Central Facility near Lamont, Oklahoma (36.605 N, 97.485 W). Additional measurements included radiation budget, soil moisture and temperature, leaf area index, plant biomass, and plant and soil carbon and nitrogen content. Results from previous years observations have shown that within a given year, the dominant source of spatial variation in fluxes are caused by land cover through the distinct timing of winter-spring (winter wheat) versus summer crops (e.g., pasture, sorghum, soybeans). Variations in net primary production (closely associated with crop yield) and net CO2 exchange for winter wheat were observed to increase by a factor of 2 and 1.4 respectively, likely due to a transition from a moderate drought to period of above average precipitation.

Timeline

Campaign Data Sets