A new method for estimating horizontal growth of the peat mat in basin-filling peatlands.
A newly developed technique was used to determine the long-term horizontal growth rate of the peat mat in Fallison Bog, a poor fen in northern Wisconsin. This technique consisted of carbon-dating material that was alive when the lake edge was at a particular location in the peatland and then measuring the distance from that location to the current lake edge. In Fallison Bog, Chamaedaphne calyculata stems currently buried at the mat peat – debris peat interface were alive when the lake edge was at that horizontal location. Radiocarbon dates of stem material from six locations in the peatland were used to estimate when the lake edge was at each location. To calculate the average long-term horizontal growth rate, the slope of the least-squares linear regression of distance from lake edge versus age of stems was computed. The estimated rate in Fallison Bog was 2.5 cm/year (95\% confidence interval was 1.6–3.5 cm/year). The linear regression explained 95.6\% of the variance in the data. The author suggests that this technique may be applicable in peatlands bordering acid lakes throughout northeastern North America.