Methane oxidation associated with submerged brown mosses reduces methane emissions from Siberian polygonal tundra

• Published in: The Journal of ecology 2011-07, Vol.99 (4), p.914-922
• Main Authors: Liebner, Susanne, Zeyer, Josef, Wagner, Dirk, Schubert, Carsten, Pfeiffer, Eva-Maria, Knoblauch, Christian
• Format: Article
• Language: English
• Subjects: Animal and plant ecology; Animal, plant and microbial ecology; aquatic mosses; Arctic; bacteria; Biological and medical sciences; biomarker; Biomass; carbon; carbon dioxide; Ecology; Ecophysiology; emissions; Fatty acids; Fundamental and applied biological sciences. Psychology; General aspects; greenhouse gases; Human ecology; isotopes; Methane; methanotrophs; methanotrophy; Mosses; mosses and liverworts; Oxidation; Oxygen; peatland; peatlands; Permafrost; photosynthesis; plant–microbe interaction; polygonal tundra; Ponds; Scorpidium scorpioides; Sphagnum; stable isotope probing; symbiosis; Synecology; Taiga & tundra; Terrestrial ecosystems; tundra; Tundras
• ISSN: 0022-0477; 1365-2745
• DOI: 10.1111/j.1365-2745.2011.01823.x

1. Methane (CH₄) oxidation (methanotrophy) associated with submerged brown moss species occurs in polygonal tundra environments of the Siberian Arctic. Methanotrophic bacteria living in close association with mosses are thus not restricted to Sphagnum species and low-pH peatlands. 2. Moss-associated methane oxidation (MAMO) can be an effective buffer for CH₄ emissions from permafrost-affected tundra, a region that is of high importance for the global greenhouse gas budget. Combining biogeochemical and molecular approaches revealed that MAMO in polygonal ponds exceeds methanotrophic activity in terrestrial sites by up to two orders of magnitude. 3. Moss-associated methane oxidation is not only promoted by submerged conditions but also by light exposure. Polygonal ponds covered by the brown moss Scorpidium scorpioides became a net sink for atmospheric CH₄ (−1.7 mg CH₄ m⁻² day⁻¹) when exposed to sunlight but a CH₄ source (21.6 mg CH₄ m⁻² day⁻¹) in the absence of light. 4. Based on stable isotope probing with ¹³CH₄, carbon deriving from CH₄ was incorporated into the bacterial fatty acids 16:1ω7 and 18:1ω9/ω7 common in methanotrophs and into plant phytol, sitosterol and stigmastanol, all of which are highly abundant in moss biomass. 5. Synthesis. A mutualistic symbiosis between methanotrophic bacteria and brown mosses reduces CH₄ emissions from Arctic polygonal tundra by at least 5%. Both partners benefit from this association: the moss from the additional CO₂ supplied through methane oxidation and the methane-oxidizing bacteria from the oxygen produced through photosynthesis. Considering that submerged mosses are widely abundant in the polar region, MAMO may have a major impact on carbon turnover rates in Arctic freshwater environments.