HR: 09:30h
AN: B41F-06 INVITED     [Abstracts]
TI: Effects of nutrient addition on C cycling in a boreal peatland
AU: Bubier, J L
EM: jbubier@mtholyoke.edu
AF: Mount Holyoke Collegy, Dept of Earth and Environment, 50 College Street, South Hadley, Ma 01075 United States
AU: * Moore, T R
EM: tim.moore@mcgill.ca
AF: McGill University, Department of Geography, 805 Sherbrook Street West, Montreal, QC H3A2K6 Canada
AB: We measured net ecosystem CO2 exchange, plant biomass, species composition, and leaf chemistry in a fertilization experiment at Mer Bleue Bog near Ottawa, Ontario. The bog is located in a the zone with the highest atmospheric nitrogen deposition for Canada, estimated at 0.8 g N m-2 yr-1 (as NH4 and NO3) with additional input of dissolved organic N and dry deposition. To establish the effect of nutrient additions on this ecosystem, we fertilized the bog with 6 treatments involving the application of up to 6 g N m-2 yr-1 (as NH4NO3), with and without P and K, as triplicate 3 x 3 m plots. The initial 5 years have shown a loss of first Sphagnum, then Polytrichum mosses, and an increase in shrub cover and biomass. Preliminary analyses of chamber CO2 data indicate the treatments with the highest levels of nutrient addition show lower rates of net CO2 exchange and gross photosynthesis, but little change in ecosystem respiration. Loss of moss cover, drier soils, changes in leaf photosynthetic capacity and shading may all contribute to the lower levels of CO2 uptake. These results have important implications for climate change because higher levels of N deposition may decrease the ability of peatlands to sequester CO2 from the atmosphere.
DE: 0414 Biogeochemical cycles, processes, and modeling (0412, 0793, 1615, 4805, 4912)
DE: 0428 Carbon cycling (4806)
DE: 0469 Nitrogen cycling
DE: 0497 Wetlands (1890)
SC: Biogeosciences [B]
MN: Fall Meeting 2005