METHANE UPTAKE IN SWEDISH FOREST SOIL IN RELATION TO LIMING AND EXTRAN-DEPOSITION

Methane uptake to soil was examined in individual chambers at three sm all forest catchments with different treatments, Control, Limed and Ni trex sites, where N-deposition was experimentally increased. The catch ments consisted of both well-drained forest and wet sphagnum areas, an d showed uptake of CHS from the ambient air. The lowest CH4 uptakes we re observed in the wet areas, where the different treatments did not i nfluence the uptake rate. in the well-drained areas the CH4 uptakes we re 1.6, 1.4 and 0.6 kg ha(-1) year(-1) for the Limed, Control and Nitr ex sites, respectively. The uptake of methane at the well-drained Nitr ex site was statistically smaller than at the other well-drained catch ments. Both acidification and increase in nitrogen in the soil, caused by the airborne deposition, are the probable cause for the reduction in the methane uptake potential. Uptake of methane was correlated to s oil water content or temperature for individual chambers at the well-d rained sites. The uptake rate of methane in soil cores was largest in the 0- to 10-cm upper soil layer. The concentration of CH4 in the soil was lower than the atmospheric concentration up to 30 cm depth, where methane production occurred. Besides acting as a sink for atmospheric methane, the oxidizing process in soil prevents the release of produc ed methane from deeper soil layers reaching the atmosphere.