HR: 0800h
AN: B31A-0066    [Abstracts]
TI: The effect of soil freezing on nitrogen dynamics: A snow manipulation study in a forested watershed in the snow belt of western New York, USA
AU: * Christopher, S F
EM: christsf@buffalostate.edu
AF: Buffalo State College, Classroom Bldg. C215, 1300 Elmwood Ave, Buffalo, NY 14222, United States
AU: Mitchell, M J
EM: mitchell@syr.edu
AF: State University of NY, College of Environmental Science and Forestry, 246 Illick Hall, 1 Forestry Drive, Syracuse, NY 13210, United States
AU: Inamdar, S
EM: inamdar@udel.edu
AF: University of Delaware, 260 Townsend Hall, 531 South College Avenue, Newark, DE 19716, United States
AB: Despite decades of research on the effects of chronically high nitrogen (N) deposition on various ecosystems, there is a knowledge gap in our understanding how atmospheric N is processed in soil, especially during winter. Understanding soil processes such as nitrification is important since nitrate is the most mobile form of N, and production of it in the soil during winter can result in substantial N leaching to surface waters. In this study, we manipulated the snowpack depth to test the effects of soil freezing on in situ rates of nitrification and N mineralization with reference and snow manipulation treatment plots at Point Peter Brook Watershed (PPBW), located in the snow belt of western, NY. One pair of treatment and reference plots was located in the riparian zone of PPBW while another pair was located on the hillslope. The snow manipulation treatment, which simulated a smaller snowpack, as is likely to occur due to the increased importance of thaws, sleet, and rain-on- snow events, induced soil freezing that lasted over the entire winter in both treatment plots. The treatment plots at both landscape positions had significantly greater N mineralization than reference plots. The effect of soil freezing on nitrification was less clear with the riparian treatment plot having greater nitrification rates than reference plot while the hillslope treatment plot had smaller nitrification rates than the reference plot. The discrepancy is likely attributed to soil moisture conditions with hillslope soils being dryer and having a lower heat capacity. As elevated N deposition continues in complex environments and climate change alters such environments, especially during winter, the effect of soil freezing should be considered when evaluating differences in N dynamics in temperate ecosystems.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0429 Climate dynamics (1620)
DE: 0469 Nitrogen cycling
DE: 1615 Biogeochemical cycles, processes, and modeling (0412, 0414, 0793, 4805, 4912)
DE: 1806 Chemistry of fresh water
SC: Biogeosciences [B]
MN: 2007 Fall Meeting