| The composition of forest stands was analyzed in a study area of 2136 ha in northern Maine, at elevations of 400-500 m, with most soils formed in glacial till. Transects across the topography were surveyed extensively, and plots along them were selected for intensive analysis of stand composition, topography, soil, ground vegetation, and site index. Three environmental scales were developed: moisture, nutrients (using a plant indicator approach), and local climate (indicated by relative elevation). The ratio of balsam fir to red and black spruce increased mainly with higher nutrient-scale values, from spruce-dominated stands on wet flats to stands high in fir on sites apparently enriched by movement of ground-water. The spruce component shifted from black spruce to red/black hybrids to red spruce with better drainage and nutrient conditions. White spruce and northern white cedar were restricted to sites with high nutrient-scale values. The proportion of hardwoods increased most strongly with higher relative elevation, indicating warmer local climates. Hardwood species were increasingly restricted to high relative elevations, in the order, white birch, red maple, yellow birch, sugar maple, and beech. Site index increased primarily with better drainage, but secondarily with higher nutrient-scale values. Trends derived from analysis of the plots were confirmed by statistics on a larger sample of transect points. A site classification for the area is presented. |
