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Methane exchange in a boreal forest estimated by gradient method

Sundqvist, Elin LU ; Mölder, Meelis LU ; Crill, Patrick; Kljun, Natascha LU and Lindroth, Anders LU (2015) In Tellus. Series B: Chemical and Physical Meteorology 67.
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,... (More)
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. (Less)
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author
organization
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type
Contribution to journal
publication status
published
subject
keywords
micrometeorology, Bowen ratio, eddy covariance, footprint, wet soil
in
Tellus. Series B: Chemical and Physical Meteorology
volume
67
publisher
Taylor & Francis
external identifiers
  • wos:000357606300001
  • scopus:84940399120
ISSN
0280-6509
DOI
10.3402/tellusb.v67.26688
language
English
LU publication?
yes
id
9debb292-cbac-45a6-9613-4b6121ac289a (old id 7790962)
date added to LUP
2015-09-02 16:14:11
date last changed
2017-10-22 04:22:08
@article{9debb292-cbac-45a6-9613-4b6121ac289a,
  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.},
  articleno    = {UNSP 26688},
  author       = {Sundqvist, Elin and Mölder, Meelis and Crill, Patrick and Kljun, Natascha and Lindroth, Anders},
  issn         = {0280-6509},
  keyword      = {micrometeorology,Bowen ratio,eddy covariance,footprint,wet soil},
  language     = {eng},
  publisher    = {Taylor & Francis},
  series       = {Tellus. Series B: Chemical and Physical Meteorology},
  title        = {Methane exchange in a boreal forest estimated by gradient method},
  url          = {http://dx.doi.org/10.3402/tellusb.v67.26688},
  volume       = {67},
  year         = {2015},
}