HR: 0800h
AN: B31B-0325    [Abstracts]
TI: Distribution of 15N Tracers Applied to the Canopy of a Mature Spruce-Hemlock Stand: Implications for Carbon Sequestration
AU: Davidson, E
AF: The Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540, United States
AU: * Dail, D B
EM: bryan.dail@maine.edu
AF: The University of Maine, 5722 Deering Hall, OronoME, ME 04469, United States
AU: Hollinger, D Y
EM: dhollinger@fs.fed.us
AF: USDA Forest Service Northern Research Station, 271 Mast Road, Durham, NH 03824, United States
AU: Davidson, E
AF: The Woods Hole Research Center, 149 Woods Hole Road, Falmouth, MA 02540, United States
AU: Sievering, H
EM: Herman.Sievering@cudenver.edu
AF: University of Colorado, Denver, 172 P.O. Box 173364, Denver, CO 80217, United States
AU: Scott, N
EM: scottn@queensu.ca
AF: The University of Maine, 5722 Deering Hall, OronoME, ME 04469, United States
AU: Scott, N
EM: scottn@queensu.ca
AF: Queen's University, Mackintosh-Corry Hall, Room D201, Kingston, ONT K7L316, Canada
AU: Fernandez, I
EM: ivanjf@maine.edu
AF: The University of Maine, 5722 Deering Hall, OronoME, ME 04469, United States
AU: Aber, J
EM: john.aber@unh.edu
AF: University of New Hampshire, 56 College Road, 215 James Hall, Durham, NH 03824, United States
AU: Gaige, E
EM: elizabeth.gaige@umit.maine.edu
AF: The University of Maine, 5722 Deering Hall, OronoME, ME 04469, United States
AB: Fertilization, through increases in N deposition, can enhance plant growth and thus impact other elemental cycles including that of carbon. However, in many N fertilization experiments chemical amendments are added to soils, making soils and not plants the short term recipient of additional N (years to decades). In 2001, a dissolved fertilizer addition of 18 kg N/ha to a 21 ha plot in a Maine spruce-hemlock forest was initiated to investigate the importance of canopy N processes and impacts on C sequestration. In smaller subplots (0.3 ha), additional N inputs were made with tracer levels of enriched N, as either ¹⁵NH₄⁺ or ¹⁵NO₃^-. Ecosystem pools, canopy gaseous N losses, and dissolved N fluxes in the ¹⁵N subplots were analyzed to determine ecosystem N retention and estimate the impact on C sequestration. Ecosystem retention of ¹⁵NH₄⁺ and ¹⁵NO₃^- was 38% and 70% respectively, much of this (~75%) was recovered in the canopy, yet little N (<5%) was recovered in woody matter with a high C:N ratio. Despite a large canopy N retention potential in this forest, C sequestration into new wood growth was ~4-5 g C m^-2 y^-1 or about 2% above the current net annual C sequestration for this site after 3 years of fertilization.
DE: 0400 BIOGEOSCIENCES
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
SC: Biogeosciences [B]
MN: 2007 Fall Meeting