Pinus resinosa product potential following initial spacing and subsequent thinning

A trial was initiated in 1953 to investigate the effect of initial tree spa cing on red pine (Pinus resinosa Air.) volume production. Approximately thr ee decades later, in 1982, thinning treatments were added to compare the ef fects of thinning and initial spacing on volume production. After 45 growin g seasons from planting, total volume production (cut + standing volume) ma inly was independent of initial spacing and thinning intensity except at th e widest (4.3 m +) spacing treatments. Both initial spacing and thinning af fected quadratic mean diameter, standing volume and basal area. Knot size w as 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 st andards due to excessive, large knots. At the time of sampling, 1998, the h igher 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 pr one to snow and ice damage. Thinning reduced the time required to meet sawl og and utility pole specifications. The initial spacings ranging from 1.8 t o 2.4 m resulted in good growth with high utility pole potential and little mortality. Lower initial spacings required thinning to prevent mortality a nd maintain good diameter growth.