• Dubis, Jeffrey J.
  University of Maine
  

This study was conducted to determine how species composition of forested mountain slopes in the western mountain biophysical region are affected by soil/site properties. The primary objectives of this study were: (1) to determine if a system of habitat types (HT's), developed for the White Mountain National Forest of New Hampshire, accurately describes the soil/site characteristics of mountain slopes in western Maine; and (2), to determine if species composition is similar on corresponding HT's, in Maine and New Hampshire. A secondary objective was to determine if individual or a combination of site variables are better than HT as predictors of species composition.

During the summers of 1992 and 1993, 134 sample plots were established primarily in hardwood and mixed wood stands. Several plots were established on sites dominated by conifers. Sample plots were 0.20 acre except those located in dense conifer stands with little variation in species composition. Within each plot, species and diameters outside bark at 4.5 ft (dbh) of all trees over 4 in were recorded. The heights of several dominant and codominant trees were measured. Increment cores were also taken from these trees in order to determine age for estimation of site index. All herbaceous vegetation was measured and recorded according to Braun-Blanquet cover classes. All saplings were measured within a six foot wide strip established parallel to the contour, extending across the plot, passing through the plot center. Three soil pits were excavated within each plot. Pits were classified by soil drainage class and HT. Parent material, solum depth, depth of each horizon, and % Coarse fragments were measured and recorded.

Although site characteristics in western Maine were similar to those in the White Mountains of New Hampshire, species composition differed. Many of the HT's in Maine had a much higher proportion of sugar maple and a lower proportion of red maple and conifers compared to the corresponding HTs in New Hampshire.

Results of statistical analyses suggest that tree species composition varies among the HT's observed on mountain slopes in western Maine. The composition of understory herbaceous and woody vegetation did not appear to differ across HT's.