EVALUATION OF RELATIVE DENSITY, DIAMETER GROWTH, AND STEM FORM IN A RED SPRUCE (PICEA-RUBENS) STAND 15 YEARS AFTER PRECOMMERCIAL THINNING

Thirty red spruce (Picea rubens Sarg.) trees were harvested from a pre commercial 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 he ight. Relative density and growth rate were measured using X-ray densi tometry, and taper was calculated for log and tree lengths. Growth rat es were significantly greater on the treatment plot than on the contro l plot. No significant differences in relative density were found betw een trees from the treatment plot (2.4 x 2.4 m spacing) and trees from the unthinned control. The relative density of the treatment and cont rol 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 wa s 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.