METHANE AND CARBON-DIOXIDE CONCENTRATIONS IN BOGS AND FENS - WITH SPECIAL REFERENCE TO THE EFFECTS OF THE BOTANICAL COMPOSITION OF THE PEAT

1 The relation between concentrations of CH4 and CO2 and the botanical and chemical composition of peat is investigated. Peat was sampled from different mires in northern Sweden. The samples were from different depths and had different botanical compositions and degrees of humification. 2 The concentration of CO2 in the peat water ranged between 0.97 and 6.5 mm, and the concentration of CH4 varied between 0.05 and 1.2 mm. 3 Methane concentrations were strongly correlated with depth (r2 = 0.63), but when the botanical composition and degree of humification were also used in the model, the explained variance (r2) in CH4 concentration was 72% and in CO2 concentration 56%. Concentrations of both gases were positively correlated with Sphagnum remains and negatively correlated with Carex remains in the peat. 4 When chemical and physical variables were also used to model the gas concentrations of a subset of samples, 65% of the variance in CO2 concentration was explained and positively correlated with Sphagnum remains and negatively with Carex remains. In total, 75% of the variance of CH4 concentrations was explained. Most of the variance (65%) was positively correlated with depth, Ni, S, Ca, K and Na.