CARBON DYNAMICS IN A FORESTED PEATLAND IN NORTH-EASTERN ONTARIO, CANADA

1. The long-term carbon accumulation rate in a forested peatland in north-east Ontario was examined in relation to gas production and factors which control carbon transport. 2 Plots of cumulative total mass and cumulative carbon mass against calibrated radio-carbon age estimates when applied to an existing model of peat accumulation, suggest that only very slow decay is occurring within the catotelm. 3 Gas samples collected from depth shows that both carbon dioxide and methane are present. Accelerator mass spectrometry (AMS) radiocarbon analysis yields age estimates of both gases which are between 500 and 2000 years younger than conventional age estimates on adjacent peat. It is suggested that this is due to the downward transport of younger carbon, probably as part of the dissolved organic carbon (DOC) in pore waters. 4 High tritium content of peat pore water at depth indicates the presence of water recharged during the last 40 years and therefore supports this hypothesis. Hydrological data from piezometers confirms the existence of hydraulic gradients for vertical water movement and shows that the direction of flow varies seasonally. 5 The results indicate that the internal carbon dynamics of peatlands are more complex than has previously been thought and that hydrology may be an important factor in the supply of source carbon for anaerobic decay.