PARENT SESSION
Contributed Oral Session 121: Freshwater Wetlands
Thursday, August 11, 8:00 AM - 11:30 AM, Meeting Room 520 C, Level 5, Palais des congrès de Montréal

Mass loss and change in carbon and nitrogen isotopes from decomposing Sphagnum fuscum litter.

Asada, Taro^*,1, Warner, Barry¹, Aravena, Ramon¹, ¹ Wetlands Research Group, University of Waterloo, Waterloo, Ontario, Canada

ABSTRACT- Sphagnum fuscum litter was incubated in three different oxic zones in a sloping Sphagnum-dominated peatland in British Columbia, Canada. Mass loss and percent composition and isotopic values of carbon and nitrogen were measured after one and two years of incubation in the field. Greater mass was lost in all the three incubated zones after the first year than the second year of incubation. Mean mass loss was the greatest in the zone closest to the peatland surface. Elemental percent carbon and ¹³C in litter slightly decreased after the first year and then returned to its original value of the fresh litter after the second year. Amount carbon loss was linearly correlated with mass loss, but the ratio between the rates of carbon loss and mass loss was slightly greater after the first year than the second year. Elemental percent nitrogen and ¹⁵N increased during the two-year incubation period. Amount nitrogen in litter did not change for most of the litter samples after the first year, but increased after the second year. Slight differences in patterns and magnitudes of carbon and nitrogen quality changes were observed under the different oxic conditions, which might reflect differences in peat decomposition processes in the surface oxic zone and the lower anoxic zone.

Key words: Sphagnum fuscum, decomposition, ¹³C, ¹⁵N