Patterns of porewater methane concentration and atmospheric emissions within different sites of a peat bog in Ohio
Abstract
Peatlands store up to a third of Earth's soil carbon pool but they also emit methane (CH4), a powerful greenhouse gas. Understanding the fluxes of CH4 from peatlands is important for predicting Earth's greenhouse gas budget, and climate feedbacks under changing conditions. However, peatlands have suffered severe anthropogenic disturbances due to conversion to agricultural land and peat extraction, which can alter the natural CH4 emission dynamics. The first objective of this study was to determine the effects of disturbance on CH4 production and emission in a peat bog in Ohio. The second objective was to develop an upscaling framework that integrates the heterogeneity of the peat bog into estimates of total CH4 emissions from the site. To achieve this, we studied Flatiron Bog, near Akron, Ohio, a reserve owned by the Nature Conservancy that has an undisturbed area and an area that has been disturbed due to drainage, fire, and other human activity. Through the peak growing seasons of 2017 and 2018 (June-Oct and May-Oct, respectively), we monitored the CH4 porewater concentration at different depths in the soil and used chambers to measure CH4 emissions at the corresponding sites above the soil column. For the first objective of the project, we examined differences in CH4 emissions between disturbed and undisturbed sites, with an emphasis on understanding potential differences in methanogenic pathways along the vertical sediment profile using metagenomics and metatranscriptomic sequencing. We found that emissions from the undisturbed site are significantly higher than those from the disturbed site although both exhibited large temporal variability. For the second objective, we found that peat within the tamarack- (Larix laricina) woodland subzone produces and emits a significantly higher amount of methane than other areas such as the open water, or the outer blueberry (Vaccinium spp.) subzones. The information from this study can be used to understand how disturbance affects the natural dynamics of methane emissions in peatlands, and to improve estimates of peat bog CH4 emissions that include within-site land cover heterogeneity.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2018
- Bibcode:
- 2018AGUFM.B41G2788R
- Keywords:
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- 0365 Troposphere: composition and chemistry;
- ATMOSPHERIC COMPOSITION AND STRUCTUREDE: 0428 Carbon cycling;
- BIOGEOSCIENCESDE: 0475 Permafrost;
- cryosphere;
- and high-latitude processes;
- BIOGEOSCIENCESDE: 0497 Wetlands;
- BIOGEOSCIENCES