Plant-mediated CH sub(4) transport and C gas dynamics quantified in-situ in a Phalaris arundinacea-dominant wetland

• Published in: Plant and soil Vol. 343; no. 1-2; pp. 287 - 301
• Main Authors: Askaer, Louise, Elberling, Bo, Friborg, Thomas, Jorgensen, Christian J, Hansen, Birger U
• Format: Journal Article
• Language: English
• Published: 01.06.2011
• Subjects: Phalaris; Phalaris arundinacea
• ISSN: 0032-079X; 1573-5036
• DOI: 10.1007/s11104-011-0718-x

Northern peatland methane (CH sub(4)) budgets are important for global CH sub(4) emissions. This study aims to determine the ecosystem CH sub(4) budget and specifically to quantify the importance of Phalaris arundinacea by using different chamber techniques in a temperate wetland. Annually, roughly 70+/-35% of ecosystem CH sub(4) emissions were plant-mediated, but data show no evidence of significant diurnal variations related to convective gas flow regardless of season or plant growth stages. Therefore, despite a high percentage of arenchyma, P. arundinacea-mediated CH sub(4) transport is interpreted to be predominantly passive. Thus, diurnal variations are less important in contrast to wetland vascular plants facilitating convective gas flow. Despite of plant-dominant CH sub(4) transport, net CH sub(4) fluxes were low (-0.005-0.016 mu mol m super(-2) s super(-1)) and annually less than 1% of the annual C-CO sub(2) assimilation. This is considered a result of an effective root zone oxygenation resulting in increased CH sub(4) oxidation in the rhizosphere at high water levels. This study shows that although CH sub(4), having a global warming potential 25 times greater than CO sub(2), is emitted from this P. arundinacea wetland, less than 9% of the C sequestered counterbalances the CH sub(4) emissions to the atmosphere. It is concluded that P. arundinacea-dominant wetlands are an attractive C-sequestration ecosystem.