Net ecosystem CO2 exchange in a temperate cattail marsh in relation to biophysical properties

Net ecosystem exchange (NEE) of carbon dioxide (CO2) was measured at a temperate cattail marsh using the eddy covariance technique in order to examine the relationships between NEE, weather, and vegetation properties. Analyses of CO2 fluxes for a complete year (May 9, 2005 to May 30, 2006) showed that the marsh wetland was a net CO2 sink for each month from June to September (monthly 24-h averages of -0.1, -5.1, -4.8, and -2.2 g C m(-2) day(-1), respectively) and a source of CO2 to the atmosphere for the remaining fall and winter months. Wintertime (November to April) average NEE was 0.5 g C m(-2) day(-1). The annual cumulative CO2 balance shows a net uptake of 264 g C m(-2) year(-1) by the marsh. Ecosystem respiration (ER) and gross ecosystem production (GEP) were estimated to be 567 and 831 g C m(-2) year(-1), respectively. Respiration rates were associated with a Q(10) value of 2.8. Peak aboveground biomass (average of 1156 g m(-2)) and peak green LAI (average of 3.63) were reached in mid-August. Variations in growing season NEE were well correlated with variations in live biomass (r = 0.92) and green LAI (r = 0.94). (c) 2007 Elsevier B.V. All rights reserved.