|Degelmann, DM; Kolb, S; Borken, W: Methane Oxidation Kinetics Differ in European Beech and Norway Spruce Soils, European Journal of Soil Science, 60, 499-506 (2009), doi:10.1111/j.1365-2389.2009.01138.x|
Coniferous forest soils consume less of the greenhouse gas methane (CH4) than deciduous forest soils. The reasons for this phenomenon have not been resolved. It might be caused by differences in the diffusive flux of CH4 through the organic layer, pH, and different concentrations of potentially inhibitory compounds. Soil samples were investigated from three adjacent European beech (Fagus sylvatica) and Norway spruce (Picea abies) stands in Germany. Maximal CH4 oxidation velocities (Vmax(app)) and Michaelis Menten constants (KM(app)), retrieved from intact soil cores at constant CH4 concentrations, temperature, and matric potential, were two times higher in beech than in spruce soils. Also atmospheric CH4 oxidation rates measured in homogenised soil samples displayed the same trend. Highest atmospheric CH4 oxidation rates were detected in the Oa horizon or in the upper 5 cm of the mineral soil. In contrast to the beech soils, the Oa horizon of the spruce soils consumed no CH4. A differential effect due to divergent diffusive flux through the litter layer was not found. pH and ammonium concentration were similar in samples from both forest soil types. Ethylene accumulation in all soils was negligible under oxic conditions. These collective results suggest that the different atmospheric CH4 uptake by beech and spruce soils is caused by different CH4 oxidising capacities of methanotrophic communities in the Oa horizon and top mineral soil.