JCSET | Watershed Studies Institute Research Symposium
The effects of organic matter distribution on microbial community composition, mass loss, and methane emissions
Academic Level at Time of Presentation
Senior
Major
Wildlife and Conservation Biology
List all Project Mentors & Advisor(s)
Dr. Jessica B. Moon
Presentation Format
Oral Presentation
Abstract/Description
Freshwater wetlands are unique in their ability to remove sediment and excess nutrients from the water that pass through them. They also store large amounts of carbon in their soil. While it is the anaerobic conditions of their soils that allow for these systems to store large amounts of carbon, these conditions also promote methanogenesis, the production of methane, a highly potent greenhouse gas. We wanted to determine if the distribution of carbon within these wetlands could affect the levels of methane produced. A recent study in dry soils showed that if you increase the spatial heterogeneity of a carbon resource by concentrating it in space microbial activity can be reduced. From these findings, we hypothesized that when carbon is clumped together and made less available to microbes in a wetland soil, there will be a decrease in microbial activity, and thus methane emissions. We created mesocosms containing wetland soils with three treatments varying in their carbon availability (i.e., bald cypress needles). These treatments are identified as uniform, where the carbon source is evenly distributed (n=3); clumped, where carbon is clumped together in one location (n=3); and a control with no carbon resource added (n=3). We then measured methane emissions weekly over a 3-month incubation period. Halfway through incubation we took samples for microbial community composition near and way from the resource patches. After six months, we also calculated the mass loss of the needles. We did find a significant difference in decomposition rates between treatments (Nested ANOVA: P-value = .0237, F-value = 723.7 D.F. = 1). The uniform treatment had a 2% higher mass loss than the clumped treatment. However, we found no significant difference in methane emissions between clumped and uniform treatments. There was a significant difference in the ratio of methanogens to methanotrophs between the uniform treatments near and away from needles (Mixed ANOVA: T-ratio = 3.712, D.F. = 4, p-value = 0.021). We are currently running a second round of incubations, with the goal of adding more spatial complexity to the systems in future studies.
Spring Scholars Week 2024 Event
Watershed Studies Institute Symposium
The effects of organic matter distribution on microbial community composition, mass loss, and methane emissions
Freshwater wetlands are unique in their ability to remove sediment and excess nutrients from the water that pass through them. They also store large amounts of carbon in their soil. While it is the anaerobic conditions of their soils that allow for these systems to store large amounts of carbon, these conditions also promote methanogenesis, the production of methane, a highly potent greenhouse gas. We wanted to determine if the distribution of carbon within these wetlands could affect the levels of methane produced. A recent study in dry soils showed that if you increase the spatial heterogeneity of a carbon resource by concentrating it in space microbial activity can be reduced. From these findings, we hypothesized that when carbon is clumped together and made less available to microbes in a wetland soil, there will be a decrease in microbial activity, and thus methane emissions. We created mesocosms containing wetland soils with three treatments varying in their carbon availability (i.e., bald cypress needles). These treatments are identified as uniform, where the carbon source is evenly distributed (n=3); clumped, where carbon is clumped together in one location (n=3); and a control with no carbon resource added (n=3). We then measured methane emissions weekly over a 3-month incubation period. Halfway through incubation we took samples for microbial community composition near and way from the resource patches. After six months, we also calculated the mass loss of the needles. We did find a significant difference in decomposition rates between treatments (Nested ANOVA: P-value = .0237, F-value = 723.7 D.F. = 1). The uniform treatment had a 2% higher mass loss than the clumped treatment. However, we found no significant difference in methane emissions between clumped and uniform treatments. There was a significant difference in the ratio of methanogens to methanotrophs between the uniform treatments near and away from needles (Mixed ANOVA: T-ratio = 3.712, D.F. = 4, p-value = 0.021). We are currently running a second round of incubations, with the goal of adding more spatial complexity to the systems in future studies.