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

1. The long-term carbon accumulation rate in a forested peatland in no rth-east Ontario was examined in relation to gas production and factor s 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 o nly very slow decay is occurring within the catotelm. 3 Gas samples co llected from depth shows that both carbon dioxide and methane are pres ent. Accelerator mass spectrometry (AMS) radiocarbon analysis yields a ge estimates of both gases which are between 500 and 2000 years younge r than conventional age estimates on adjacent peat. It is suggested th at this is due to the downward transport of younger carbon, probably a s part of the dissolved organic carbon (DOC) in pore waters. 4 High tr itium content of peat pore water at depth indicates the presence of wa ter recharged during the last 40 years and therefore supports this hyp othesis. Hydrological data from piezometers confirms the existence of hydraulic gradients for vertical water movement and shows that the dir ection of flow varies seasonally. 5 The results indicate that the inte rnal carbon dynamics of peatlands are more complex than has previously been thought and that hydrology may be an important factor in the sup ply of source carbon for anaerobic decay.