The Presettlement Forest and Natural Disturbance Cycle of Northeastern Maine

Land survey records of 1793—1827 containing forest data for 1.65 x 106 ha of northern Maine were analyzed for species composition, successional status, and frequency of large—scale disturbance. Quantitative data consists of 1,448 sample trees spaced 1.6 km apart along a 9.7— x 9.7—km grid. Species which each comprised \u3e 10% of the total were Picea spp., Fagus grandifolia, Abies balsamea, Thuja occidentalis, and Betula lutea. These forests appeared to be largely in a climax state as indicated by the dominance of shade—tolerance species and the small percentage (8%) of intolerant or early successional species. However, 9.3% of the tract was burned land and birch—aspen forest at the time of the survey, mostly the result of large fires in 1803 and 1825. Windfalls occurred along 2.6% of the surveyed distance. If the amount of disturbed forest at this time was typical of the natural disturbance regime, then the average recurrence interval of fire and large—scale windthrow for a given site would be 800 and 1,150 years, respectively. Data on the structure of remnant virgin stands in the region likewise suggest that the time interval between severe disturbances was much longer than that needed to attain a climax, all—aged structure