- Steinman, James R.
University of Maine Graduate School
The purpose of this dissertation was to use an archived data set from nine M.S. theses to conduct a comprehensive evaluation of site quality of naturally occurring spruce-fir stands in Maine. Soil and growth and yield data from 155 temporary sample plots were used to quantify: 1) potential height growth patterns of spruce and fir species; 2) variability in site conditions in spruce-fir stands; and 3) relationships between soil variables and spruce and fir growth responses.
Potential height growth patterns of spruce and fir were quantified by using the two fastest growing trees of spruce and fir from each sample plot. The distribution of growth curve patterns among sampled plots showed that: 1) 35% were linear; 2) 35% were sigmoid; 3) 20% were convex, and 4) 10% were concave. Site indices ranged from 35- to 70-feet (height at 50-years breast height age), with 50% of the trees having site indices between 45 and 55 feet. Linear and nonlinear site index and height development curves were formulated, and resulted in families of curves that were different than those developed by Vicary (1982). Comparisons of errors of prediction indicated that the curves developed in this study were of similar precision as those by Vicary, but contained less bias. Also, height development curves were more precise than site index curves, and there were no significant differences between curves for spruce and fir species.