Linking rhizospheric CH4 oxidation and net CH4 emissions in an arctic wetland based on (CH4)-C-13 labeling of mesocosms

Abstract

Aims Poorly drained arctic ecosystems are potential large emitters of methane (CH4) due to their high soil organic carbon content and low oxygen availability. In wetlands, aerenchymatous plants transport CH4 from the soil to the atmosphere, but concurrently transport O-2 to the rhizosphere, which may lead to oxidation of CH4. The importance of the latter process is largely unknown for arctic plant species and ecosystems. Here, we aim to quantify the subsurface oxidation of CH4 in a waterlogged arctic ecosystem dominated by Carex aquatilis ssp. stans and Eriophorum angustifolium, and evaluate the overall effect of these plants on the CH4 budget.Methods A mesocosms study was established based on the upper 20 cm of an organic soil profile with intact plants retrieved from a peatland in West Greenland (69 degrees N). We measured dissolved concentrations and emissions of (CO2)-C-13 and (CH4)-C-13 from mesocosms during three weeks after addition of C-13-enriched CH4 below the mesocosm.Results Most of the recovered C-13 label (> 98 %) escaped the ecosystem as CH4, while less than 2 % was oxidized to (CO2)-C-13.Conclusions It is concluded that aerenchymatous plants control the overall CH4 emissions but, as a transport system for oxygen, are too inefficient to markedly reduce CH4 emissions.

Keywords

Carex; Greenhouse gases; Methane; Oxidation; Stable isotopes; Tundra

Published in

Plant and Soil
2017, volume: 412, number: 1-2, pages: 201-213
Publisher: SPRINGER

SLU Authors

• Skov Nielsen, Cecilie

  • University of Copenhagen

UKÄ Subject classification

Soil Science

Publication identifier

• DOI: https://doi.org/10.1007/s11104-016-3061-4

Permanent link to this page (URI)

https://res.slu.se/id/publ/84880