Optimizing Any-Aged Management of Mixed-Species Stands: II. Effects of Decision Criteria

Abstract

Abstract The effects of maximum present value and maximum volume objectives on the efficiencies of alternative silvicultural systems are determined by solving any-aged management problems for mixed-conifer stands in the Northern Rocky Mountains. Any-aged management problems are formulated with periodic planting and harvesting controls and without constraints on the stand age or size structure over time. Optimization is performed with the Stand Prognosis Model, a single-tree simulator that has been calibrated for many forest types in the western United States. With a maximum present value objective, 1987 stumpage prices, and no logging damage, steady-state, uneven-aged management using selection cuts is the target silvicultural system for a range of stand types. Optimal transition regimes for understocked stands include clearcutting and planting western white pine (Pinus monticola Dougl. ex D. Don), a high-value, fast-growing species. With a maximum merchantable volume objective, two types of management emerge as optimal: even-aged plantation management and an uneven-aged shelterwood system are both capable of producing the same high level of yield indefinitely. Both types of management rely on a series of thinnings to grow the most vigorous crop trees into the largest size classes. In addition, the shelterwood system ensures that adequate natural regeneration is established when the crop trees are harvested. Because the uneven-aged shelterwood system produces steady-state yields that are as high or higher than plantation management, these results call into question the widely held view that even-aged plantation management maximizes total merchantable volume production. For. Sci. 36(1):125-144.