Growth, Mortality, and Damage in Fast Growing Douglas-fir Stands in Coastal British Columbia Twenty Years After Heavy Juvenile Thinning and Moderate Pruning at Age Nine

Abstract

Abstract The purpose of this research was to examine the effects of pruning and thinning on the growth and mortality of young Douglas-fir (Pseudotsuga menziesii [Mirb] Franco) stands on high-productivity sites in coastal British Columbia. To accomplish this, a two-way randomized incomplete block design with two blocks was established on a coastal site with three levels of thinning (no thinning, thin to 500 stems per ha, and thin to 250 stems per ha) and three levels of pruning (no pruning, prune 250 stems per ha, and prune all trees). The response variables of interest were diameter at breast height (dbh), height, basal area, total and merchantable volume, mortality, damage, and deformities. Dbh and height were examined both for all trees and for only the largest 250 sph by dbh trees (the crop trees). The dynamics in partially pruned stands were also examined. We found that only dbh, basal area, total and merchantable volume, and mortality were affected by thinning. Pruning did not have any effect on the ...