Linking rhizospheric CH 4 oxidation and net CH 4 emissions in an arctic wetland based on 13 CH 4 labeling of mesocosms

• Published in: Plant and Soil
• Main Authors: Nielsen, Cecilie Skov, Michelsen, Anders, Ambus, Per, Deepagoda, T. K. K. Chamindu, Elberling, Bo
• Format: Article in Journal/Newspaper
• Language: English
• Published: 2017
• Subjects: Carex; Greenhouse gases; Methane; Oxidation; Stable isotopes; Tundra; Arctic; Greenland; Carex aquatilis; Eriophorum
• Online Access: https://curis.ku.dk/portal/da/publications/linking-rhizospheric-ch4-oxidation-and-net-ch4-emissions-in-an-arctic-wetland-based-on-13ch4-labeling-of-mesocosms(ea5df5b3-8c1b-4e91-9c7c-3b2874b47689).html; https://doi.org/10.1007/s11104-016-3061-4

Aims: Poorly drained arctic ecosystems are potential large emitters of methane (CH 4 ) due to their high soil organic carbon content and low oxygen availability. In wetlands, aerenchymatous plants transport CH 4 from the soil to the atmosphere, but concurrently transport O 2 to the rhizosphere, which may lead to oxidation of CH 4 . The importance of the latter process is largely unknown for arctic plant species and ecosystems. Here, we aim to quantify the subsurface oxidation of CH 4 in a waterlogged arctic ecosystem dominated by Carex aquatilis ssp. stans and Eriophorum angustifolium, and evaluate the overall effect of these plants on the CH 4 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°N). We measured dissolved concentrations and emissions of 13 CO 2 and 13 CH 4 from mesocosms during three weeks after addition of 13 C-enriched CH 4 below the mesocosm. Results: Most of the recovered 13 C label (>98 %) escaped the ecosystem as CH 4 , while less than 2 % was oxidized to 13 CO 2 . Conclusions: It is concluded that aerenchymatous plants control the overall CH 4 emissions but, as a transport system for oxygen, are too inefficient to markedly reduce CH 4 emissions.