Temporal Changes in Methane Oxidizing and Denitrifying Communities and Their Activities in a Drained Peat Soil

• Northern peat soils are both sources and sinks of the greenhouse gases nitrous oxide (N2O) and methane (CH4). These fluxes are regulated by the activity of microbial communities. Temporal, spatial and depth related differences in potential activity and composition of the denitrifier and methanotrophic bacterial communities were compared between winter and summer in relation to in situ fluxes of N2O and CH4 from a drained and forested peat land in Sweden. The composition of the genetic pool of these guilds was assessed using terminal fragment length polymorphism analysis of signature genes in the denitrification and methane oxidation pathways, respectively. The composition of the communities was similar throughout the soil profile, although both denitrification and methane oxidation rates decreased with soil depth. The potential methane oxidation rates were significantly correlated to soil N content, and , indicating a nitrogen induced stimulation of methane oxidation capacity. The site was a source of N2O and a small sink for CH4, and although the fluxes did not vary significantly over time, both the methane oxidizing and denitrifier community composition exhibited temporal patterns. Differences in the composition of the methanotrophic community reflected that the peat site shifted from a summer to a winter community. The denitrifiers exhibited a similar trend, but also differed significantly between the sampling occasions during summer, as well as between locations at the site. The latter was explained by differences in soil pH. It was only the differences in the methane oxidizer community composition that correlated with its corresponding potential activity, which implies a higher degree of functional redundancy within the denitrifier community.

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NATURVETENSKAP  -- Geovetenskap och miljövetenskap -- Miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences -- Environmental Sciences (hsv//eng)

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