HR: 1330h
AN: B22A-0791    [PDF]
TI: Soil Trace Gas Flux for Wetland Vegetation Zones in North Dakota Prairie Pothole Basins
AU: * Phillips, R L
EM: rebecca@aero.und.edu
AF: University of North Dakota Upper Midwest Aerospace Consortium, Odegard School of Aerospace Sciences University and Campus Drive Box 9007, Grand Forks, ND 59202
AU: Beeri, O
EM: beeri@umac.org
AF: University of North Dakota Upper Midwest Aerospace Consortium, Odegard School of Aerospace Sciences University and Campus Drive Box 9007, Grand Forks, ND 59202
AU: DeKaiser, E S
AF: North Dakota State University Department of Animal and Range Sciences, 1301 12th Ave N, Fargo, ND 58105
AB: Wetland ecosystems are considered a source for radiatively trace gases [methane (CH$_{4}$), carbon dioxide (CO$_{2}$), nitrous oxide (N$_{2}$O)] but flux data for these greenhouse gases are lacking for depressional wetlands that comprise the Prairie Pothole Region. This region is characterized by thousands of small, closed basins that extend along the Missouri Coteau from north central Iowa to central Alberta. Surrounding each body of water are conspicuous zonation patterns given by specific vegetation life-forms and soil properties that are predominately formed by basin hydrology. Basin vegetation zones include deep marsh, shallow marsh, wet meadow, low prairie, and cropland (Stewart and Kantrud,1971). \\ Our primary objective was to determine if net greenhouse gas flux for soils in these wetland basins [mg/m$^{2}$/day CO$_{2}$ equivalent (IPCC, 2000)] vary with vegetative zone for prairie pothole ecosystems. These data may then be used to map estimates for total basin greenhouse gas (GHG) flux. Additionally, we aimed to find the relative contribution of each of the 3 trace gases (CO$_{2}$, CH$_{4}$ and N$_{2}$O) to net GHG flux. We hypothesized that flux would be greatest for marsh areas and lowest for upland areas.\\ We selected a semi-permenant prairie pothole research site in Max, ND and mapped respective vegetative zones for 3 adjacent basins. Sample points were randomly selected for each basin and zone using aerial imagery. Samples of soil gases were collected using the static chamber method on August 3, 2003, and these were analyzed using gas chromatography for CO$_{2}$, CH$_{4}$ and N$_{2}$O the following day. Soil moisture, clay content, organic matter, and temperature data were also collected. \\ Net greenhouse gas flux for the cropped zone soils was significantly lower (p$<$0.01) than flux for the deep marsh, shallow marsh and wet meadow zone soils. Average flux measurement by zone (mg CO$_{2}$ equivalent/m$^{2}$/day) was 283 for cropland, 677 for low prairie, 1067 for wet meadow, 2572 for shallow marsh, and 6686 for deep marsh. Methane, in terms of CO$_{2}$ equivalents, contributed most strongly to and was the best predictor of greenhouse gas flux (r$^{2}$=0.98). Since most of these basin areas are planted with wheat, average net GHG flux per square meter was 600 to 900 mg CO$_{2}$ equivalents per day. Our results indicate that there are flux differences among wetland zones within these closed basin ecosystems and that CH$_{4}$ contributes most to net GHG flux for these wetland soils.
UR: http://www.umac.org/gbe/
DE: 1615 Biogeochemical processes (4805)
DE: 1890 Wetlands
SC: Biogeosciences [B]
MN: 2003 Fall Meeting