A 20-year-old Douglas-fir [Pseudotsuga menziesii (Mirb.) Franco] stand in the Oregon Coast Range was thinned from about 1,700 to about 350 trees/ac. Subsequent thinnings, under eight different regimes, occurred at ages 23, 27, 30, and 32. Average net periodic cubic-volume growth was strongly influenced by thinning regime, varying from about 220 ft /ac/yr (heavy thinning age 30) to over 550 ft /ac/yr (controls age 23). The results indicate that young Douglas-fir on productive sites (site index 160 to 170 ft at 100 years) are extremely adaptable and will respond to frequent thinnings of various intensities. Three representative treatments (after thinning at age 32) and the controls were projected and optimized with dynamic programming for two financial analyses. Adjusting rotation or commercial thinning can compensate for lack of early stand management or heavy early thinning.
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