JCSET | Watershed Studies Institute Research Symposium
The Relationship Between Hydrogeomorphic Settings and Greenhouse Gas Emissions from Bald Cypress trees in Western Kentucky’s Freshwater Mineral Soil Wetlands
Academic Level at Time of Presentation
Graduate
Major
Biology
Minor
Watershed Science Concentration
List all Project Mentors & Advisor(s)
Jessica B Moon, PhD
Presentation Format
Oral Presentation
Abstract/Description
Freshwater mineral soil wetlands sequester substantial amounts of carbon, but their soils and vegetation can also emit methane (CH4), a potent greenhouse gas. Studies have documented differences in soil and stem CH4 exchange between extremes in topographic landscape settings, such as between dry uplands and inundated wetlands. With a more narrow focus, we are investigating how CH4 emissions from tree stems and soils vary across hydrogeomorphic settings, specifically: a pond edge, a reservoir edge, and a channel. In each setting, we measured CH4 flux rates seasonally from soils and two heights (i.e., 40 cm and 120 cm above the ground) along the stems of bald cypress (Taxodium distichum), a common obligate wetland species. We hypothesized that CH4 fluxes vary as a function of hydrogeomorphic setting, which vary in hydropatterns and resource availability. We also predicted that emissions would decrease with increasing height along a stem.We found the highest emissions along the reservoir edge during the summer 2023, followed by the pond edge then channel. Further sampling at reservoir and pond edge sites shows that the combination of temperature and water present at the reservoir edge during the summer – which allowed for highest emissions – does not continue through the rest of the year; while pond edge, though lower in the summer, has continuously high emissions over the entire year. Height remained a significant driver of variation over the year favoring greater emissions closer to ground. The significance of tree diameter effect was strongest at the pond edge site year round but only seen during the summer at the reservoir site. Despite its significance being evident unevenly across the seasons and sites, it always displayed the pattern of greatest emissions in smaller trees. Further, upscaling cylindrical surface area estimates of the trees over the entire year shows that the pond edge site’s trees produce more than twice as much methane annually than the reservoir edge.Understanding these relationships will enable accurate carbon cycle modeling in a warming world, as well as provide optimal T. distichum planting recommendations for future land managers.
Spring Scholars Week 2025
Watershed Studies Institute Research Symposium
The Relationship Between Hydrogeomorphic Settings and Greenhouse Gas Emissions from Bald Cypress trees in Western Kentucky’s Freshwater Mineral Soil Wetlands
Freshwater mineral soil wetlands sequester substantial amounts of carbon, but their soils and vegetation can also emit methane (CH4), a potent greenhouse gas. Studies have documented differences in soil and stem CH4 exchange between extremes in topographic landscape settings, such as between dry uplands and inundated wetlands. With a more narrow focus, we are investigating how CH4 emissions from tree stems and soils vary across hydrogeomorphic settings, specifically: a pond edge, a reservoir edge, and a channel. In each setting, we measured CH4 flux rates seasonally from soils and two heights (i.e., 40 cm and 120 cm above the ground) along the stems of bald cypress (Taxodium distichum), a common obligate wetland species. We hypothesized that CH4 fluxes vary as a function of hydrogeomorphic setting, which vary in hydropatterns and resource availability. We also predicted that emissions would decrease with increasing height along a stem.We found the highest emissions along the reservoir edge during the summer 2023, followed by the pond edge then channel. Further sampling at reservoir and pond edge sites shows that the combination of temperature and water present at the reservoir edge during the summer – which allowed for highest emissions – does not continue through the rest of the year; while pond edge, though lower in the summer, has continuously high emissions over the entire year. Height remained a significant driver of variation over the year favoring greater emissions closer to ground. The significance of tree diameter effect was strongest at the pond edge site year round but only seen during the summer at the reservoir site. Despite its significance being evident unevenly across the seasons and sites, it always displayed the pattern of greatest emissions in smaller trees. Further, upscaling cylindrical surface area estimates of the trees over the entire year shows that the pond edge site’s trees produce more than twice as much methane annually than the reservoir edge.Understanding these relationships will enable accurate carbon cycle modeling in a warming world, as well as provide optimal T. distichum planting recommendations for future land managers.
