Activity and abundance of methanotrophic bacteria in a northern mountainous gradient of wetlands

Methane uptake and diversity of methanotrophic bacteria was investigated across six hydrologically connected wetlands in a mountainous forest landscape upstream of lake Langtjern, southern Norway. From floodplain through shrubs, forest and sedges to a Sphagnum covered site, growing season CH(4) production was insufficiently consumed to balance release into the atmosphere. Emission increased by soil moisture ranging 0.6–6.8 mg CH(4) m(−2) h(−1). Top soils of all sites consumed CH(4) including at the lowest 78 ppmv CH(4) supplied, thus potentially oxidizing 17–51 nmol CH(4) g(−1) dw h(−1), with highest V(max) 440 nmol g(−1) dw h(−1) under Sphagnum and lowest K(m) 559 nM under hummocked Carex. Nine genera and several less understood type I and type II methanotrophs were detected by the key functional gene pmoA involved in methane oxidation. Microarray signal intensities from all sites revealed Methylococcus, the affiliated Lake Washington cluster, Methylocaldum, a Japanese rice cluster, Methylosinus, Methylocystis and the affiliated Peat264 cluster. Notably enriched by site was a floodplain Methylomonas and a Methylocapsa‐affiliated watershed cluster in the Sphagnum site. The climate sensitive water table was shown to be a strong controlling factor highlighting its link with the CH(4) cycle in elevated wetlands.