As part of the AmeriFlux program, we have been measuring continuous fluxes of carbon dioxide, mass and energy over a temperate deciduous forest since the fall of 1994. The forest is growing near Oak Ridge, TN, it is 24 m tall, has a leaf area of about 5.5 and has been growing since the 1940s. The eddy covariance method is being employed. Instruments used to measure fluxes (a sonic anemometer and open path infrared gas analyzers) are mounted on a 44 m tower.
In this presentation we discuss information on the seasonal and interannual variation of carbon and water budgets and the impact of environmental and ecophysiological factors on these budgets. We also use this information to validate a coupled micrometeorological and ecophysiological model.
Eddy covariance measurements are apt to underestimate carbon dioxide fluxes at night. We, therefore, use the output of the model to interpret the field measurements and to constrain the estimates of the annual carbon and water budgets. The effects of flow drainage and storage of CO2 in the canopy air space on annual and diurnal fluxes are also discussed.