Methane exchange in a boreal forest estimated by gradient method

Research output: Contribution to journalArticle

Abstract

Forests are generally considered to be net sinks of atmospheric methane (CH4) because of oxidation by methanotrophic bacteria in well-aerated forests soils. However, emissions from wet forest soils, and sometimes canopy fluxes, are often neglected when quantifying the CH4 budget of a forest. We used a modified Bowen ratio method and combined eddy covariance and gradient methods to estimate net CH4 exchange at a boreal forest site in central Sweden. Results indicate that the site is a net source of CH4. This is in contrast to soil, branch and leaf chamber measurements of uptake of CH4. Wetter soils within the footprint of the canopy are thought to be responsible for the discrepancy. We found no evidence for canopy emissions per se. However, the diel pattern of the CH4 exchange with minimum emissions at daytime correlated well with gross primary production, which supports an uptake in the canopy. More distant source areas could also contribute to the diel pattern; their contribution might be greater at night during stable boundary layer conditions.

Details

Authors
Organisations
External organisations
  • Swansea University
Research areas and keywords

Subject classification (UKÄ) – MANDATORY

  • Earth and Related Environmental Sciences

Keywords

  • micrometeorology, Bowen ratio, eddy covariance, footprint, wet soil
Original languageEnglish
Article numberUNSP 26688
JournalTellus. Series B: Chemical and Physical Meteorology
Volume67
Publication statusPublished - 2015
Publication categoryResearch
Peer-reviewedYes