HR: 14:40h
AN: B22B-04    [PDF]
TI: Dependency of Ecosystem Respiration in a Cool Temperate Bog on Peat Temperature and Water Table
AU: * Moore, T
EM: tim.moore@mcgill.ca
AF: McGill University, 805 Sherbrooke St. W., Montreal, QC H3A 2K6 Canada
AU: Lafleur, P
EM: plafleur@trentu.ca
AF: Dept. Geography, Trent University, Peterborough, ON K8P 2W6 Canada
AU: Roulet, N
EM: roulet@mcgill.ca
AF: McGill University, 805 Sherbrooke St. W., Montreal, QC H3A 2K6 Canada
AU: Frolking, S
EM: steve.frolking@unh.edu
AF: Institute for the Study of Earth, Ocean and Space, University of New Hampshire, Durham, NH 03824 United States
AB: We measured ecosystem respiration (ER) from nighttime net ecosystem exchange of carbon dioxide determined from an eddy covariance tower located in a large ombrotrophic bog near Ottawa, Canada. Measurements were made from May to October over 5 years, 1998 to 2002. Ecosystem respiration ranged from $<$0.05 mg CO2/m2/s in spring (May) and late fall (late October) to 0.10-0.15 mg CO2/m2/s during the summer (July-August). As anticipated, there was a strong relationship between ER and peat temperatures, such as at a depth of 5 cm (r2 = 0.63). Q10 over 5$\deg$ to 15$\deg$C varied from 2.2 to 4.2 depending upon the choice of temperature level and location within a hummock or hollow. Unexpected for a wetland ecosystem, there was only a weak relationship between ER and water table position (r2 = 0.11). Comparison of ER in early and late summer, 2002 with similar surface temperature revealed no significant difference in ER. A laboratory incubation of peat cores at different moisture contents showed that CO2 production was reduced by drying in the surface samples, but there was little decrease in samples from below a depth of 30 cm. We believe that the lack of correlation between ER and water table position in this ecosystem results from an increase in CO2 production at depth compensating a decrease in production of CO2 by heterotrophic respiration in the near surface layers and autotrophic respiration in the moss community.
DE: 1610 Atmosphere (0315, 0325)
DE: 1615 Biogeochemical processes (4805)
DE: 1851 Plant ecology
DE: 1890 Wetlands
SC: Biogeosciences [B]
MN: 2003 Fall Meeting