Bog profile evidence of fire and vegetation dynamics since 3000 years BP in the Acadian Forest

Abstract

An attempt has been made to characterize fire prehistory and its effect on Acadian Forest vegetation by microscopic examination of charred particles and pollen preserved over the last 3000 years in bogs near Marcelville and Fredericton, New Brunswick, Canada. A background accumulation rate of about 0.15 mm 2 ∙g dry weight −1 ∙year −1 of charred particles was found in each sample, indicating a constant rain of distant-source, small particles. Proximity of the source fire to the site of particle deposition was estimated with the aid of two charred particle transport studies conducted during prescribed burns. Charred particles of 44 400 μm 2 and larger were found up to 1 km from the source, with a wind speed of 20 km/h. Smaller particles remained in the air column for much longer and are of less use for determining local fires. Analysis determined periods of province-wide fires and subsequent forest composition changes. The greatest of these occurred at about 2200, 1750, 1550, and 400 years BP. Temporal patterns of charred particle peaks were similar in the two bogs and support data from Nova Scotia and Maine. Fires seem to have accompanied the establishment of the present-day forest type in the period around 1450 years BP.