• Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC


Paper No. 25
Presentation Time: 3:00 PM


RANSOHOFF, Rebecca Weiss, Earlham College, Department of Geology, Richmond, IN 47374, SODERLUND, Lily, Department of Geology, University of Cincinnati, Cincinnati, OH 45221 and TOWNSEND-SMALL, Amy, Department of Geology and Department of Geography, University of Cincinnati, 605 Geology-Physics Building, Cincinnati, OH 45221,

Urban greenspaces are thought to be beneficial for the uptake and sequestration of greenhouse gases. This paper evaluates the efficiency at which managed urban lawns on the campus of the University of Cincinnati release and/or absorb the greenhouse gases methane (CH4), carbon dioxide (CO2), and nitrous oxide (N2O), compared to a local, unmanaged urban forest and lawn. N2O has a greenhouse gas forcing of approximately 300 times CO2, and methane of about 25 times that of CO2. Samples were collected by following the USDA-ARS chamber-based trace gas flux measurement protocol using static, skirted flux chambers, and analyzed by FID and ECD methods. We hypothesized that the urban lawns’ ability to absorb the gases would be diminished compared to the forest and unmanaged grassland. Preliminary data show that CH4 is being emitted from campus soils, but is being absorbed by the unmanaged lawn and urban forest. A similar trend was seen in N2O emissions with higher emissions on campus lawns than those of unmanaged lawns, and no significant N2O flux in the urban forest. These data will also be compared to soil carbon sequestration rates, also currently under investigation, for a full greenhouse gas balance. It appears that even if lawns are a strong sink for CO2 stored in soils, this effect is counteracted by N2O and CH4 emissions, thus decreasing the ability of lawns to act as an overall greenhouse gas sink.
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