Land-atmosphere exchange of methane from soil thawing to soil freezing in a high-Arctic wet tundra ecosystem

• Published in: Global change biology Vol. 18; no. 6; pp. 1928 - 1940
• Main Authors: Tagesson, Torbern, Mölder, Meelis, Mastepanov, Mikhail, Sigsgaard, Charlotte, Tamstorf, Mikkel P., Lund, Magnus, Falk, Julie M., Lindroth, Anders, Christensen, Torben R., Ström, Lena
• Format: Journal Article
• Language: English
• Published: Oxford Blackwell Publishing Ltd 01.06.2012; Wiley-Blackwell
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; Atmosphere; Atmospheric turbulence; Autumn; balance; Biological and medical sciences; carbon; carbon balance; Carbon dioxide; Climate change; Earth and Related Environmental Sciences; Ecosystems; eddy covariance; Freezing; Fundamental and applied biological sciences. Psychology; General aspects; Geovetenskap och miljövetenskap; Geovetenskap och relaterad miljövetenskap; gradient method; Growing season; land-atmosphere interactions; Methane; Micrometeorology; Natural Sciences; Naturgeografi; Naturvetenskap; Physical Geography; Primary production; Snowmelt; Soil temperature; Soils; Synecology; Taiga & tundra; Terrestrial ecosystems; Thawing; Tundra; Winter; Arctic Region; Greenland; Methane; Air ground interaction; gradient method; Method; Carbon balance; Dynamical climatology; Exchange; land-atmosphere interactions; Climate change; Soils; Eddy covariance; Micrometeorology; Atmosphere; Ecosystem; Tundra
• ISSN: 1354-1013; 1365-2486; 1365-2486
• DOI: 10.1111/j.1365-2486.2012.02647.x

The land‐atmosphere exchange of methane (CH4) and carbon dioxide (CO2) in a high‐Arctic wet tundra ecosystem (Rylekærene) in Zackenberg, north‐eastern Greenland, was studied over the full growing season and until early winter in 2008 and from before snow melt until early winter in 2009. The eddy covariance technique was used to estimate CO2 fluxes and a combination of the gradient and eddy covariance methods was used to estimate CH4 fluxes. Small CH4 bursts were observed during spring thawing 2009, but these existed during short periods and would not have any significant effect on the annual budget. Growing season CH4 fluxes were well correlated with soil temperature, gross primary production, and active layer thickness. The CH4 fluxes remained low during the entire autumn, and until early winter. No increase in CH4 fluxes were seen as the soil started to freeze. However, in autumn 2008 there were two CH4 burst events that were highly correlated with atmospheric turbulence. They were likely associated with the release of stored CH4 from soil and vegetation cavities. Over the measurement period, 7.6 and 6.5 g C m−2 was emitted as CH4 in 2008 and in 2009, respectively. Rylekærene acted as a C source during the warmer and wetter measurement period 2008, whereas it was a C sink for the colder and drier period of 2009. Wet tundra ecosystems, such as Rylekærene may thus play a more significant role for the climate in the future, as temperature and precipitation are predicted to increase in the high‐Arctic.