Getting to the root of plant‐mediated methane emissions and oxidation in a thermokarst bog
Links
- More information: Publisher Index Page (via DOI)
- Open Access Version: External Repository
- Download citation as: RIS | Dublin Core
Abstract
Vascular plants are important in the wetland methane cycle, but their effect on production, oxidation, and transport has high uncertainty, limiting our ability to predict emissions. In a permafrost‐thaw bog in Interior Alaska, we used plant manipulation treatments, field‐deployed planar optical oxygen sensors, direct measurements of methane oxidation, and microbial DNA analyses to disentangle mechanisms by which vascular vegetation affect methane emissions. Vegetation operated on top of baseline methane emissions, which varied with proximity to the thawing permafrost margin. Emissions from vegetated plots increased over the season, resulting in cumulative seasonal methane emissions that were 4.1–5.2 g m−2 season−1 greater than unvegetated plots. Mass balance calculations signify these greater emissions were due to increased methane production (3.0–3.5 g m−2 season−1) and decreased methane oxidation (1.1–1.6 g m−2 season−1). Minimal oxidation occurred along the plant‐transport pathway, and oxidation was suppressed outside the plant pathway. Our data indicate suppression of methane oxidation was stimulated by root exudates fueling competition among microbes for electron acceptors. This contention is supported by the fact that methane oxidation and relative abundance of methanotrophs decreased over the season in the presence of vegetation, but methane oxidation remained steady in unvegetated treatments; oxygen was not detected around plant roots but was detected around silicone tubes mimicking aerenchyma; and oxygen injection experiments suggested that oxygen consumption was faster in the presence of vascular vegetation. Root exudates are known to fuel methane production, and our work provides evidence they also decrease methane oxidation.
Study Area
Publication type | Article |
---|---|
Publication Subtype | Journal Article |
Title | Getting to the root of plant‐mediated methane emissions and oxidation in a thermokarst bog |
Series title | Journal of Geophysical Research Biogeosciences |
DOI | 10.1029/2020JG005825 |
Volume | 125 |
Issue | 111 |
Year Published | 2020 |
Language | English |
Publisher | American Geophysical Union |
Contributing office(s) | Geology, Minerals, Energy, and Geophysics Science Center |
Description | e2020JG005825, 18 p. |
Country | United States |
State | Alaska |
Google Analytic Metrics | Metrics page |