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AGU: Geophysical Research Letters

 

Keywords

  • anaerobic
  • climate
  • flux
  • forests
  • greenhouse gas emissions
  • methane

Index Terms

  • 0315 - Biosphere/atmosphere interactions
  • 0404 - Anoxic and hypoxic environments
  • 0429 - Climate dynamics
  • 0490 - Trace gases
  • 1631 - Land/atmosphere interactions

Paper in Press

GEOPHYSICAL RESEARCH LETTERS, doi:10.1029/2012GL052361

Elevated methane concentrations in trees of an upland forest

Key Points
  • The production of methane inside trees is not limited to lowland soils
  • Production rates vary seasonally, and with tree species
  • Archea active in trees produce significant quantities of methane

Authors:

Kristofer R Covey

Stephen A Wood

Robert J Warren

Xuhui Lee

Mark Bradford

There is intense debate about whether terrestrial vegetation contributes substantially to global methane emissions. Although trees may act as a conduit for methane release from soils to atmosphere, the debate centers on whether vegetation directly produces methane by an uncharacterized, abiotic mechanism. A second mechanism of direct methane production in plants occurs when methanogens - microorganisms in the domain Archaea - colonize the wood of living trees. In the debate this biotic mechanism has largely been ignored, yet conditions that promote anaerobic activity in living wood, and hence potentially methane production, are prevalent across forests. We find average, growing season, trunk-gas methane concentrations >15,000 LL¬-1 in common, temperate-forest species. In upland habitat (where soils are not a significant methane source), concentrations are 2.3-times greater than in lowland areas, and wood cores produce methane in anaerobic, lab-assays. Emission rate estimates from our upland site are 529.5 ng CH4 m-2 s-1; rates that are of a similar magnitude to the soil methane sink in temperate forest, and equivalent in global warming potential to ~18% of the carbon likely sequestered by this forest. Microbial infection of one of the largest, biogenic sinks for carbon dioxide, living trees, might result in substantial, biogenic production of methane.

Received 15 May 2012; accepted 3 July 2012.

Citation: Covey, K. R., S. A. Wood, R. J. Warren II, X. Lee, and M. Bradford (2012), Elevated methane concentrations in trees of an upland forest, Geophys. Res. Lett., doi:10.1029/2012GL052361, in press.