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Harvard Forest REU Symposium Abstract 2023
- Title: Investigating Drivers of Tree-Stem Methane Emissions in Wetland and Upland Environments
- Author: Hannah M Burrows (Harvard University)
- Abstract:
Despite being relatively less abundant in the atmosphere, methane (CH4) is a potent greenhouse gas, trapping significantly more heat than carbon dioxide (CO2). Alongside industrial emissions, natural landscapes, namely wetland environments, account for roughly half of methane emissions to the atmosphere. The anoxic soil in wetland environments fosters methane generating microbes–methanogens–while upland soils foster methane consuming microbes–methanotrophs. However, in both wetland and upland environments, trees have been found to emit varying amounts of methane from their stems with the drivers behind these processes largely unknown. By studying the patterns behind this phenomenon, we are able to better understand methane’s role in our forest’s ability to sequester carbon. Thus, we sought to investigate tree-stem methane emissions across four species (Nyssa sylvatica, Acer Rubrum, Tsuga canadensis, and Querces rubra), at two sites, and over the course of a month. We monitored 60 different trees at several points over the course of a month as the soil moisture and weather changed. In alignment with prior research, wetland trees acted like a conduit for methane generated in their soils, the 30 wetland trees emitted a median methane flux 4 times greater than the 30 upland trees. We found that black gum trees (Nyssa sylvatica) had a mean methane flux nearly 30 times higher than all the other trees. This supports the idea of species-specific traits, such as susceptibility to rot and photosynthetic rate, also leading to higher methane flux rates. However, each site and species contained a wide range of methane emission rates–including near zero flux. These results illustrate the variability among tree-stem methane emissions and the necessity for future study.
- Research Category: Forest-Atmosphere Exchange
