Evaluating the Classical Versus an Emerging Conceptual Model of Peatland Methane Dynamics

Wendy H. Yang*, Gavin McNicol, Yit Arn Teh, Katerina Estera-Molina, Tana E. Wood, Whendee L. Silver

*Corresponding author for this work

Research output: Contribution to journalArticle

6 Citations (Scopus)
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Abstract

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 CH4 oxidation. 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 CH4 within anaerobic microsites. Even in soil from beneath the water table, gross CH4 production 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.

Original languageEnglish
Pages (from-to)1435-1453
Number of pages19
JournalGlobal Biogeochemical Cycles
Volume31
Issue number9
Early online date25 Sep 2017
DOIs
Publication statusPublished - Sep 2017

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Keywords

  • gross methane fluxes
  • methane oxidation
  • methanogenesis
  • redox
  • Sacramento-San Joaquin Delta
  • stable isotope pool dilution

ASJC Scopus subject areas

  • Global and Planetary Change
  • Environmental Chemistry
  • Environmental Science(all)
  • Atmospheric Science

Cite this

Yang, W. H., McNicol, G., Teh, Y. A., Estera-Molina, K., Wood, T. E., & Silver, W. L. (2017). Evaluating the Classical Versus an Emerging Conceptual Model of Peatland Methane Dynamics. Global Biogeochemical Cycles, 31(9), 1435-1453. https://doi.org/10.1002/2017GB005622