Emissions of Anaerobically Produced Methane by Trees

TLDR: In this article, the authors report results from a greenhouse mesocosm study that indicate significant emissions of anaerobically produced CH4 transmitted to the atmosphere through broadleaf riparian tree species grown under flooded conditions.

Abstract: [1] Recent studies indicate that plants may be a previously overlooked but significant source of atmospheric CH4, though there is considerable disagreement on the mechanism of production. Our work sought to verify that woody deciduous trees grown under inundated conditions had the capacity for transporting CH4 from an anaerobic subsurface to the atmosphere and to consider if such a source could be important globally. Here, we report results from a greenhouse mesocosm study that indicate significant emissions of anaerobically produced CH4 transmitted to the atmosphere through broadleaf riparian tree species grown under flooded conditions. Using a leaf area normalized mean emission rate (0.7 ± 0.3 μg cm−2 hr−1), results were scaled globally for flooded forest regions and estimated to be 60 ± 20 Tg year−1, ∼10% of the global CH4 source. The carbon isotopic composition of CH4 emitted was found to be significantly enriched compared with expectations (δ13C ∼ −54‰) and provided an important isotopic constraint on the global source which coincides with the mean of the globally scaled greenhouse-based estimate.