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Lookup NU author(s): Professor Yit Arn TehORCiD
This is the final published version of an article that has been published in its final definitive form by Wiley-Blackwell, 2017.
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Methane (CH4) is a potent greenhouse gas that is both produced and consumed in soils by microbially mediated processes sensitive to soil redox. We evaluated the classical conceptual model of peatland CH4 dynamics - in which the water table position determines the vertical distribution of methanogenesis and methanotrophy - versus an emerging model in which methanogenesis and methanotrophy can both occur throughout the soil profile due to spatially heterogeneous redox and anaerobic CH4oxidation. We simultaneously measured gross CH4 production and oxidation in situ across a microtopographical gradient in a drained temperate peatland and ex situ along the soil profile, giving us novel insight into the component fluxes of landscape‐level net CH4 fluxes. Net CH4 fluxes varied among landforms (p < 0.001), ranging from 180.3 ± 81.2 mg C m−2 d−1 in drainage ditches to −0.7 ± 1.2 mg C m−2 d−1 in the highest landform. Contrary to prediction by the classical conceptual model, variability in methanogenesis alone drove the landscape‐level net CH4 flux patterns. Consistent with the emerging model, freshly collected soils from above the water table produced CH4within anaerobic microsites. Even in soil from beneath the water table, gross CH4production was best predicted by the methanogenic fraction of carbon mineralization, an index of highly reducing microsites. We measured low rates of anaerobic CH4 oxidation, which may have been limited by relatively low in situ CH4 concentrations in the hummock/hollow soil profile. Our study revealed complex CH4 dynamics better represented by the emerging heterogeneous conceptual model than the classical model based on redox strata.
Author(s): Yang WH, McNicol G, Teh YA, Estera-Molina K, Wood TE, Silver WL
Publication type: Article
Publication status: Published
Journal: Global Biogeochemical Cycles
Online publication date: 30/08/2017
Acceptance date: 26/08/2017
Date deposited: 13/06/2019
ISSN (print): 0886-6236
ISSN (electronic): 1944-9224
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