Evaluation of relative density, diameter growth, and stem form in a red spruce (Picearubens) stand 15 years after precommercial thinning

Abstract

Thirty red spruce (Picearubens Sarg.) trees were harvested from a precommercial thinning trial near St. Margaret's Bay, Nova Scotia. Total height was measured, and samples were removed from the following five stem heights: stump height, breast height, 25, 50, and 75% of total height. Relative density and growth rate were measured using X-ray densitometry, and taper was calculated for log and tree lengths. Growth rates were significantly greater on the treatment plot than on the control plot. No significant differences in relative density were found between trees from the treatment plot (2.4 × 2.4 m spacing) and trees from the unthinned control. The relative density of the treatment and control trees was also compared with the species average relative density for red spruce. No significant differences were found, except for the relative density at stump height in the after-treatment portion of the trees from the thinned plot. The difference was not considered great enough to cause a deterioration of the mechanical properties of lumber or the yield of pulp produced from this material. The taper factor was significantly different between the treatment and control plots, but the taper factor for the treatment trees was similar to that for the spruce resource currently being processed in eastern Canada.