3 research outputs found
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Response of young Douglas-fir to 16 years of intensive thinning
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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Animal damage to coniferous plantations in Oregon and Washington. pt. II, an economic evaluation
Regression models of height growth and survival were fitted to aggregate data for trees, protected and not protected from animal damage, that had been surveyed on Douglas-fir and ponderosa pine plantations in Oregon and Washington. Animal damage significantly affected both height and survival. Dynamic programming analysis-using both soil expectation (Se) and allowable cut effect (ACE) indicators-was used to derive (1) optimal economic regimes for managing stands with full and depressed stocking levels, (2) management guidelines for protection expenditure and stand replacement, and (3) physical impacts on volume yield. At current rates of planting in Oregon and Washington and at a 3 percent discount rate, animals cause an estimated 1.8 billion. Likewise, present net worth decreases by 18 percent, and growth and yield by 13 percent. Several other discount rates showed different proportional impacts from animal damage