title: Methane oxidation in contrasting soil types: responses to experimental warming with implication for landscape-integrated CH4budget.
abstract: Arctic ecosystems are characterized by a wide range of soil moisture conditions and thermal regimes and contribute differently to the net methane (CH4) budget. Yet, it is unclear how climate change will affect the capacity of those systems to act as a net source or sink of CH4. Here, we present results of in situ CH4flux measurements made during the growing season 2014 on Disko Island (west Greenland) and quantify the contribution of contrasting soil and landscape types to the net CH4budget and responses to summer warming. We compared gas flux measurements from a bare soil and a dry heath, at ambient conditions and increased air temperature, using open-top chambers (OTCs). Throughout the growing season, bare soil consumed 0.22 ± 0.03 g CH4-C m-2(8.1 ± 1.2 g CO2-eq m-2) at ambient conditions, while the dry heath consumed 0.10 ± 0.02 g CH4-C m-2(3.9 ± 0.6 g CO2-eq m-2). These uptake rates were subsequently scaled to the entire study area of 0.15 km2, a landscape also consisting of wetlands with a seasonally integrated methane release of 0.10 ± 0.01 g CH4-C m-2(3.7 ± 1.2 g CO2-eq m-2). The result was a net landscape sink of 12.71 kg CH4-C (0.48 tonne CO2-eq) during the growing season. A nonsignificant trend was noticed in seasonal CH4uptake rates with experimental warming, corresponding to a 2% reduction at the bare soil, and 33% increase at the dry heath. This was due to the indirect effect of OTCs on soil moisture, which exerted the main control on CH4fluxes. Overall, the net landscape sink of CH4tended to increase by 20% with OTCs. Bare and dry tundra ecosystems should be considered in the net CH4budget of the Arctic due to their potential role in counterbalancing CH4emissions from wetlands - not the least when taking the future climatic scenarios of the Arctic into account.
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Section for Forest, Nature and Biomass, Department of Geosciences and Natural Resource Management, University of Copenhagen, Rolighedsvej 23, Frederiksberg, 1958 C, Denmark.
authors.forename: Ludovica
authors.initials: L
authors.lastname: D'Imperio
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.
authors.forename: Cecilie Skov
authors.initials: CS
authors.lastname: Nielsen
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.
authors.forename: Andreas
authors.initials: A
authors.lastname: Westergaard-Nielsen
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.|Terrestrial Ecology Section, Department of Biology, University of Copenhagen, Universitetsparken 15, Copenhagen, DK-2100 Ø, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Michelsen
authors.affiliation: Center for Permafrost (CENPERM), Department of Geosciences and Natural Resource Management, University of Copenhagen, Øster Voldgade 10, DK-1350, Copenhagen, Denmark.
authors.forename: Bo
authors.initials: B
authors.lastname: Elberling
mesh_terms: D001110:Arctic Regions; D057231:Climate Change; D017753:Ecosystem; D006116:Greenland; D008697:Methane / Q000737:chemistry*; D012621:Seasons; D012987:Soil / Q000737:chemistry*; D013696:Temperature; D065929:Tundra
chemical_list: D012987:Soil; D008697:Methane
keywords: Arctic; Greenland; bare soil; dry heath; methane budget; methane uptake; soil moisture; warming