- Zellers, Christopher E.
University of Maine Graduate School
The ability of eastern white pine (Pinus strobus L.) to persist as emergent trees makes this species well suited to silvicultural systems in which they are retained as isolated reserves after a regeneration harvest. While such systems are implemented throughout the Acadian spruce-fir region of Maine, little is known about the growth response and financial performance of eastern white pine following complete release from competition. In this study, 77 trees from 8 sites throughout the Acadian spruce-fir region were sampled tree and crown measurements, and increment cores were extracted at breast height, as well as from the top of the valuable first 16 foot log. Volume growth was examined prior to and following release, and overall response to release was favorable. A subsample of 9 trees climbed to measure basal diameter and vertical location of each branch to develop allometric leaf area equations and to examine influence of site productivity and age on growth efficiency. Leaf area-volume increment relationships were modeled with a nonlinear power function with a random effect for site, and employed to forecast future growth. A sawmill simulator was used to estimate post- release standing tree values and financial analysis was performed to assess performance of completely released trees for an unpruned and a hypothetical pruned scenario. Unpruned trees, on average exhibited peak net present value 52 years post-release. Pruned trees declined in net present value following release, due to high initial values. The net benefit of pruning reached its maximum 30 years after pruning, and stayed positive for 101 years, suggesting that pruning is a viable practice for eastern white pine that will be released and retained as reserve trees. The retention of eastern white pine reserve trees appears to be both biologically and financially sound, but forest managers should be careful to select vigorous younger trees as reserves to maximize financial performance.