Pinus resinosa product potential following initial spacing and subsequent thinning

Abstract

A trial was initiated in 1953 to investigate the effect of initial tree spacing on red pine (Pinus resinosa Ait.) volume production. Approximately three decades later, in 1982, thinning treatments were added to compare the effects of thinning and initial spacing on volume production. After 45 growing seasons from planting, total volume production (cut + standing volume) mainly was independent of initial spacing and thinning intensity except at the widest (4.3 m +) spacing treatments. Both initial spacing and thinning affected quadratic mean diameter, standing volume and basal area. Knot size was affected by initial spacing with trees at an initial spacing of 3.0 m or wider having a significant number of stems failing to meet utility pole standards due to excessive, large knots. At the time of sampling, 1998, the higher initial densities (1.2 and 1.5 m-spacing) were undergoing significant mortality and falling behind the lower initial spacings in terms of total volume production. In addition, trees at the narrowest spacing were more prone to snow and ice damage. Thinning reduced the time required to meet sawlog and utility pole specifications. The initial spacings ranging from 1.8 to 2.4 m resulted in good growth with high utility pole potential and little mortality. Lower initial spacings required thinning to prevent mortality and maintain good diameter growth. Key words: red pine, density management, volume production, product mixtures