Rates of peat accumulation during the postglacial period in 32 sites from Alaska to Newfoundland, with special emphasis on northern Minnesota

Abstract

We examined long-term rates of dry peat accumulation in 32 14C-dated cores from poor fens in Alaska, to bogs and fens in midcontinental North Dakota and Minnesota, to oceanic bogs in Maine and the Atlantic Provinces of Canada. Sites along this belt transect exhibit mostly linear relationships between cumulative mass and age. Long-term rates of peat accumulation range from 16 to 80 g·m–2·year–1, with a median rate of 47 g·m–2·year–1 and a mean rate of 50 g·m–2·year–1. Rate of accumulation is inversely correlated with mean annual precipitation, but is not correlated with the area of the peat basin, basal age, or mean annual temperature. Four of the five highest rates are from relatively dry midcontinental locations in North Dakota and Minnesota; the other is for a coastal site in Newfoundland. The two lowest rates are from extremely rainy sites on Pleasant Island in the Alaskan panhandle. Individual accumulation rates between adjacent dates are quite variable within the peat cores, and across the transect, they do not correlate significantly with immediately previous rates. The same is true of the four sites with the greatest numbers of dates. There is a small but significant negative correlation within the Red Lake Peatland.Key words: bog, fen, mire, North America, peatland.