Disjunct jack pine (Pinus banksianaLamb.) structure and dynamics, Acadia National Park, Maine

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Abstract
We use dendroecology to determine age structure and dynamics of two stands of disjunct jack pine (Pinus banksiana Lamb.) at Acadia National Park, Maine. Jack pine’s range extends across Canada and the north central U.S.; this site in Maine is a marginal outlier, and shows patterns of stand history and tree growth that contrast with the more commonly described central populations. Jack pine is associated with fire as a disturbance agent, and sees its best growth on deep loamy to sandy soils. In contrast, the Acadia stands have not burned since the nineteenth century, and both are along exposed ridge tops with little to no soil. Serotiny is low and regeneration is continuous without fire. One of the sites shows high growth rates and substantial recent regeneration; the other stand is older, and vigorous red spruce (Picea rubens Sarg.) is co-dominant. Neither stand displays an origin pattern of rapid post-fire development, nor the classic successional sequence of sharply decreasing regeneration and growth rates as a shade-tolerant increases. In a coastal year-round wet climate, this marginal jack pine population can persist in the absence of frequent fire on sites with soil too poor and shallow to nurture competitors.