HR: 1330h
AN: H43B-12    [Abstracts]
TI: Nitrogen Dynamics in a Northeast Forest Ecosystem - Spatial and Temporal Patterns in Stream Water and Soil Solution Chemistry.
AU: * Dittman, J A
EM: jadittma@syr.edu
AF: Syracuse University, Department of Civil and Environmental Engineering, Syracuse, NY 13244 United States
AU: Driscoll, C T
EM: ctdrisco@syr.edu
AF: Syracuse University, Department of Civil and Environmental Engineering, Syracuse, NY 13244 United States
AB: Distinct patterns in soil solution and stream water chemistry are manifested across landscape position at the Hubbard Brook Experimental Forest (HBEF) in the White Mountains of New Hampshire. The objective of this study was to examine the spatial and temporal patterns in the concentrations and fluxes of nitrogen (N) species and dissolved organic carbon (DOC) in soil solutions and stream water along an elevational gradient (525-775m) at the HBEF. A 12 year record (1992-2003) of measurements of soil water and stream chemistry in Watershed 6 (W6), the biogeochemical reference watershed at the HBEF, were used in this analysis. Solutions were largely comprised of NO3- and DON, as NH4+ concentrations were generally low particularly in mineral soil solutions and stream water. Dissolved organic N and DOC concentrations were elevated in the high elevation spruce-fir-white birch portion of the watershed, while NO3- was the dominate N species in the lower elevation hardwood portion of the watershed. Surprisingly, seasonal patterns of NO3- in soil leachate were not as strong as one might expect given the importance and availability of NO3- as a plant and microbial nutrient. However, distinct seasonal patterns were evident for NO3- in stream water, suggesting the importance of hydrological flow paths and/or in-stream processes in regulating watershed NO3- loss. Understanding patterns of N and DOC dynamics in stream and soil solution is critical for evaluating the response of forest ecosystems to changes in the deposition of anthropogenic N and the potential for nutrient retention within terrestrial ecosystems.
DE: 0400 Biogeosciences
SC: Hydrology [H]
MN: 2005 Joint Assembly