Methane production by soils from different Louisiana marsh vegetation types

Abstract

This study evaluated quantitative indices (soil organic matter, tabile C, and sulfate concentrations) correlated with methane production rates along related vegetation and salinity gradients in the Louisiana coastal marsh region. Expressed on a soil dry mass basis, soil labile C was the variable most closely correlated with CH4 production rates (R2=0.69). Expressed on a surface area basis, labile C and SO4 2− were both significantly correlated with CH4 production rates (R2=0.36). Lower CH4 production rates in saline marshes were attributed to higher SO4 2− content per unit area. This effect was confounded with the effect of plant species changes along the salinity gradient. Soils underSpartina patens produced less CH4 if collected from brackish marshes than from less saline intermediate marshes. Thus, variation in CH4 production across the broader gradient was not a result of plant species changes alone. Laboratory production data such as this can be useful in designing sampling schemes for future studies of field CH4 emissions.