DISJUNCT JACK PINE (PINUS-BANKSIANA LAMB) STRUCTURE AND DYNAMICS, ACADIA NATIONAL-PARK, MAINE

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