Fossil carbon/nitrogen ratios as a measure of peat decomposition

Net accumulation rates of carbon in a 9000 calendar year record of Sphagnum fuscum peat in western boreal Canada range from 13.6 to 34.9 g . m(-2). yr(-1). The depth vs. age curve is slightly convex due to generally declining net productivity at the site. Fossil carbon/nitrogen ratios of bulk Sphagnum fuscum peat and its components are used to calculate the rate and total amount of decay in the deeper anoxic peat deposits. The proportional rate of decay in the catotelm of the peatland declines linearly over lime. Carbon loss from the catotelm is estimated at 50% after 1700 calendar years and 65% after 7500 calendar years. Carbon has been added to the catotelm at an average rate of 28.0 g . m(-1). yr(-1) over the last 1174 years, whereas, at present, the cumulative loss of carbon over the entire catotelm is 19.4 g . m(-2). yr(-1). The peatland continues to represent a sink for carbon.