Quantifying the Effects Sizes of Common Controls on Methane Emissions From an Ombrotrophic Peat Bog

Taylor, M.; Bradford, Mark A.; Arnold, Wyatt; Takahashi, D.; Colgan, T.; Davis, Virginia; Losos, Danielle; Peccia, Jordan; Raymond, P. A.

doi:10.1029/2022jg007271

Cited by 3 publications

(2 citation statements)

References 58 publications

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“…Additionally, there were no significant differences between high- and low-fluxing plots in terms of Cu, Fe 2+ , total iron, Mg, Ca, Mn, fluoride, chloride, or sulfate ( P > 0.1). In a related study, plant functional composition was also found uncorrelated to flux at the site ( 59 ). While many of these factors have proven correlated with flux at larger spatial and temporal scales ( 7 ), and multi-depth measurements would be needed to fully discount their contribution here, these data suggest that they were not primary drivers of flux variability at Orient Bog.…”

Section: Resultsmentioning

confidence: 90%

“…The plots themselves were demarcated using polyvinyl chloride (PVC) collars of 45 cm diameter, which were permanently installed 8 cm into the soil layer. A map of the site and plot location are available in a related manuscript ( 59 ). Plot nomenclature followed the format: transect # _ plot #, subplot, with plot numbering increasing from the SE to NW.…”

Section: Methodsmentioning

confidence: 99%

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Microbial activity contributes to spatial heterogeneity of wetland methane fluxes

Arnold,

Taylor,

Bradford

et al. 2023

Microbiol Spectr

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The emission of methane from wetlands is spatially heterogeneous, as concurrently measured surface fluxes can vary by orders of magnitude within the span of a few meters. Despite extensive study and the climatic significance of these emissions, it remains unclear what drives large, within-site variations. While geophysical factors (e.g., soil temperature) are known to correlate with methane (CH 4 ) flux, measurable variance in these parameters often declines as spatial and temporal scales become finer. As methane emitted from wetlands is the direct, net product of microbial metabolisms which both produce and degrade CH 4 , it stands to reason that characterizing the spatial variability of microbial communities within a wetland—both horizontally and vertically—may help explain observed variances in flux. To that end, we surveyed microbial communities to a depth of 1 m across an ombrotrophic peat bog in Maine, USA using amplicon sequencing and gene expression techniques. Surface methane fluxes and geophysical factors were concurrently measured. Across the first meter of peat at the site, we observed significant changes in the abundance and composition of methanogenic taxa at every depth sampled, with variance in methanogen abundance explaining 70% of flux heterogeneity at a subset of plots. Among measured environmental factors, only peat depth emerged as correlated with flux, and had significant impact on the abundance and composition of methane-cycling communities. These conclusions suggest that a heightened awareness of how microbial communities are structured and spatially distributed within wetlands could offer improved insights into predicting CH 4 flux dynamics. IMPORTANCE Globally, wetlands are one of the largest sources of methane (CH 4 ), a greenhouse gas with a warming impact significantly greater than CO 2 . Methane produced in wetlands is the byproduct of a group of microorganisms which convert organic carbon into CH 4 . Despite our knowledge of how this process works, it is still unclear what drives dramatic, localized (<10 m) variance in emission rates from the surface of wetlands. While environmental conditions, like soil temperature or water table depth, correlate with methane flux when variance in these factors is large (e.g., spring vs fall), the explanatory power of these variables decline when spatial and temporal scales become smaller. As methane fluxes are the direct product of microbial activity, we profiled how the microbial community varied, both horizontally and vertically, across a peat bog in Maine, USA, finding that variance in microbial communities was likely contributing to much of the observed variance in flux.

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Section: Resultsmentioning

confidence: 90%

Section: Methodsmentioning

confidence: 99%

Microbial activity contributes to spatial heterogeneity of wetland methane fluxes

Arnold,

Taylor,

Bradford

et al. 2023

Microbiol Spectr

Self Cite

View full text Add to dashboard Cite

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Wetland hydrological dynamics and methane emissions

Cui,

Liu,

Guo

et al. 2024

Commun Earth Environ

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Shoulder season controls on methane emissions from a boreal peatland

Jentzsch,

Männistö,

Marushchak

et al. 2024

Biogeosciences

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Abstract. Cold-season emissions substantially contribute to the annual methane budget of northern wetlands, yet they remain underestimated by process-based models. Models show significant uncertainty in their parameterization of processes, particularly during the transitional phases of freezing and thawing temperatures in the shoulder seasons. Our aim was to identify the environmental controls on the components of the methane fluxes – methane production, oxidation, and transport – from a boreal peatland during the shoulder seasons. We partitioned net methane emissions into their components by combining manual chamber flux measurements on vegetation removal treatments with pore water sampling for concentrations and stable carbon isotope ratios of dissolved methane in the wet hollows of Siikaneva bog in southern Finland during seasonal field campaigns in 2021 and 2022. The results suggest that the decrease in methane emissions due to decreasing production rates with decreasing peat temperatures in the shoulder seasons was dampened by several processes. Firstly, highly efficient transport of methane through the aerenchyma of peatland sedges continued outside of the growing season after plant senescence. Secondly, decaying vascular plants provided additional substrate for methane production at the end of the growing season. Thirdly, accumulation of methane in the pore water partly delayed the emission of methane produced in summer and winter compared to the shoulder seasons. Substrate-limited oxidation rates, however, largely compensated for the higher diffusion rates related to high pore water concentrations in fall. Accounting for these processes specific to the shoulder seasons by separately modeling the components of methane fluxes will likely work against the underestimation of cold-season methane emissions from northern peatlands.

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Quantifying the Effects Sizes of Common Controls on Methane Emissions From an Ombrotrophic Peat Bog

Cited by 3 publications

References 58 publications

Microbial activity contributes to spatial heterogeneity of wetland methane fluxes

Microbial activity contributes to spatial heterogeneity of wetland methane fluxes

Wetland hydrological dynamics and methane emissions

Shoulder season controls on methane emissions from a boreal peatland

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