HR: 15:30h
AN: NB24D-01    [Abstracts]
TI: Reintroduction of flooding and change in denitrification rates on a leveed Midwestern floodplain
AU: * Orr, C H
EM: csorr@wisc.edu
AF: Center for Limnology University of Wisconsin, 680 N. Park Street, Madison, WI 53706 United States
AU: Stanley, E
EM: ehstanley@wisc.edu
AF: Center for Limnology University of Wisconsin, 680 N. Park Street, Madison, WI 53706 United States
AU: Wilson, K
EM: k.wilson@utoronto.ca
AF: University of Toronto, Department of Zoology, Toronto, ON M5S 3G5 Canada
AU: Finlay, J
EM: jfinlay@umn.edu
AF: Univeristy of Minnesota, 100 Ecology Building, St. Paul, MN 55108 United States
AB: We examined the response of soil denitrification to a floodplain restoration project that reintroduced controlled flooding to a previously isolated 900 hectare site adjacent to the Baraboo River, Wisconsin. Monthly June-August for one year prior and two years post restoration we measured denitrification in static cores (SC μgN2O-N/kgsoil-hr) and potential denitrification in carbon and nitrate amended soil slurry samples (DEA μgN2O-N/kgsoil-hr). Rates showed high temporal and spatial variability. Individual sample SC rates ranged widely (0.00 to 16.7) with a mean value of 1.10 (SD = 3.02). DEA rates were in the same general range (0.00 to 15.0) but with a slightly higher mean (mean 1.41, comparison p<0.05). Denitrification was not highly correlated with soil nutrient content. However, the difference in rates between SC and DEA samples pre-restoration was higher than post-restoration, suggesting that denitrification was less limited after the reintroduction of flooding. Vegetation type and history of flooding were better predictors of denitrification than current soil water content. Despite large variability in measured rates, these results demonstrate that there is potential for denitrification to remove significant amounts nitrate from river systems. Management of water levels to provide adequate exchange between river and floodplain is important to this process.
DE: 1615 Biogeochemical processes (4805)
DE: 1821 Floods
DE: 1845 Limnology
DE: 4845 Nutrients and nutrient cycling
SC: North American Benthological Society [NB]
MN: 2005 Joint Assembly