A CLOSED-CHAMBER CO2 FLUX METHOD FOR ESTIMATING MARSH PRODUCTIVITY

This paper describes a closed-chamber method of rapidly measuring CO2 flux in marshes which, in conjunction with appropriate sampling strate gies, can be useful for estimating marsh net productivity, comparing p roductivity of two or more marshes, or assessing factors that influenc e productivity. The method relies on placement of an environmental cha mber over the marsh followed by no more than 6 min of measurement via an infrared gas analyzer. Three laboratory trials and one field trial were undertaken to assess the method. Laboratory trials included: (1) ensuring that measurements could show a well-defined relationship betw een CO2 concentration and CO2 flux, (2) regression of CO2 flux measure ments against biomass for Sporobolus virginicus (L.) Kunth, and (3) co mparison of CO2 flux for three plant species associated with salt mars hes to ensure that the method could detect differences among species. The field trial compared pairs of CO2 flux measurements from 14 plots to assess precision. (C) 1998 Elsevier Science B.V. All rights reserve d.