Can altering the distribution of organic matter in wetlands soils change methane emissions?

Project Abstract

Forested mineral soil wetlands, found throughout the southeastern United States, store large amounts of carbon as woody biomass. Their anaerobic soil environments also make them hotspots for methanogenesis, leading to emissions of methane during soil respiration. Recent studies have suggested that at fine spatial scales (7.069 cm2), clumping of a labile carbon source, in dry soils, can result in lower microbial activity when compared to a uniformly distributed source. However, they also found in wetter soils (65% maximum water holding capacity), initial patterning of the carbon source didn’t affect microbial activity, presumably because the substrate was able to diffuse throughout the soil matrix. We investigated whether these results would hold for an inundated mineral wetland soil, Mhoon silt loam, at a larger spatial scale (1500 cm2) and with a natural wetland carbon source, bald cypress (Taxodium distichum) needles. We created three treatments: uniformly distributed needles (n=3), clumped needles (n=3), and no needles (n=3). Microbial activity is currently being measured, weekly, as the net CH4 flux. Microbial community composition (16S ribosomal RNA) was also measured after 2 months of incubation. At the end of our study needle mass loss will also be quantified for net decomposition.

Initial results (first three months) showed that clumped and uniform needles did not have significantly different mean CH4 emissions. However, preliminary analysis of our microbial data suggests that the composition of microbes varied between patches of needles and no needles within mesocosms for both uniform and clumped treatments. This indicates that resources may not be diffusing through the entire mesocosm uniformly in inundated conditions. In the coming weeks, we will be detailing these patch dynamics by identifying the relative abundances of specific microbial groups, methanogens and methanotrophs. We will also continue to measure weekly net CH4 gas fluxes, as we hypothesize that the effect of resource patterning on microbial activity may vary as a function of resource lability. This work has implications for restoration practices (e.g., plantings, soil conditions) in forested mineral soil wetlands, a class of wetlands that have been historically impacted by drain and fill activities.


American Geophysical Union Fall Meeting, December 11th - 15th, 2023, American Geological Union.

Funding Type

Travel Grant

Academic College

Jesse D. Jones College of Science, Engineering and Technology


Wildlife Conservation






Jessica B. Moon PhD.

Academic College

Jesse D. Jones College of Science, Engineering and Technology

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