Animal damage to coniferous plantation in Oregon and Washington. Part II. An economic evaluation

Abstract

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 $60 million annually in damage, reducing the net capitalized value of the timber resource by $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.