Dependency of Ecosystem Respiration in a Cool Temperate Bog on Peat Temperature and Water Table
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.
Earth Sciences, Earth Systems Research Center
EOS, Transactions American Geophysical Union, Fall Meeting, Supplement
American Geophysical Union Publications
Moore, T., Lafleur, P., Roulet, N. and Frolking, S. (2003), Dependency of Ecosystem Respiration in a Cool Temperate Bog on Peat Temperature and Water Table, Eos Trans. AGU, 84(46), Fall Meet. Suppl., Abstract B22B-04, 2003.