Quantifying Carbon Pools and Fluxes in Southern Ontario Temperate Swamps

Swamps are treed wetlands, which account for the highest areal extent of wetland types in Southern Ontario due to the difficulties of conversion for development and agriculture. However, little is known about the environmental factors and processes that influence carbon (C) dynamics or the resulting C stocks and fluxes therein. We studied 12 swamps across Southern Ontario for 12 consecutive months to measure the exchange of carbon dioxide (CO 2 ) and methane (CH 4 ) between soil and atmosphere and estimate current C stocks in soil and biomass. We found mean growing season soil respiration of CO 2 and CH 4 across the swamps ranged from 11 g m -2 d -1 to 49 g m -2 d -1 and -3 mg m -2 d -1 to 44 mg m -2 d -1 , respectively, with a water table threshold at about 20 cm where fluxes changed substantially. Biomass stored 7.92–37.0 kg m -2 of C across the sites, and soil stored 11.6–35.5 kg m -2 . Over the study year, the swamps functioned as C sinks and followed similar patterns of relationships to environmental conditions as bogs and fens, with little difference between hydrogeomorphic settings or canopy types.