Comparison of CO2 and H2O fluxes over grassland vegetations measured by the eddy-covariance technique and by open system chamber

Abstract

Measurements of CO2 and H2O fluxes were carried out using two different techniques-eddy-covariance (EC) and open system gas exchange chamber (OC)-during two-years' period (2003-2004) at three different grassland sites. OC measurements were made during fourteen measurement campaigns. We found good agreement between the OC and EC CO2 flux values (n = 63, r 2 = 0.5323, OC FCO2 = -0.6408+0.9508 EC FCO2). The OC FH2O values were consistently lower than those measured by the EC technique, probably caused by the air stream difference inside and outside the chamber. Adjusting flow rate within the chamber to the natural conditions would be necessary in future OC measurements. In comparison with EC, the OC proved to be a good tool for gas exchange measurements in grassland ecosystems. © 2007 Institute of Experimental Botany, ASCR.