| Summary: | In the field of forest planning, assumptions regarding the appropriate modeling of management behavior, translated through management prescriptions, minimum harvest ages, green-up periods, and other variables are needed if a stand-level optimization process is not used to guide the selection of stand management regimes Forest planners thus generally have a few options regarding the level of detail of management intentions they can model, from detailed, finely-tuned assumptions to coarser, less detailed assumptions. The question of interest to this study is whether similar forest plan results can be obtained over a range of detail assumed in the management intentions. With that in mind, forest plans are developed under three different levels of detail of management intentions. Using a simulated annealing heuristic, forest plans were developed for a 95,063 acre eastern Oregon private industrial forest, covering a fifty-year planning horizon. Within this landscape 32,782 acres were even-aged forests, 22,106 acres were uneven-aged, and 40,175 acres were indicated as meadow or grassland. A survey conducted by the Oregon Department of Forestry was used to define the management intentions. The finest level of detail was one where all of the management intention data available were used, allowing prescriptions to be developed by site class and species breakdowns. The intermediate level of detail, called the medium scale, represented management intentions, and hence prescriptions, developed by species information only, since site class information is generally difficult to obtain in a geographic information system (GIS) database across broad landscapes. The most aggregated level of detail was called the coarse scale. Here both site class and species information was ignored, and a generalized idea of what the management intentions, hence prescriptions, would be on uneven-aged and even-aged stands in eastern Oregon was developed. Measure of economic, or commodity production, results were represented by net present value (NPV), timber volume production, and harvested acres. One measure of ecological value (great gray owl, Strix nebulosa, nesting habitat) was also evaluated in the ensuing forest plans. No significant differences in owl habitat were found across the three levels of detail in management intentions. However, a significant difference in the NPVs generated among the three management intention scales was observed. A non-parametric rank sum test showed that the mean of the values of the NIPV were significantly different (all combinations having a one-sided p-value <0.0001). In addition, large differences in the timing of harvest volumes, and hence revenue generated and acres treated, were observed. This analysis indicates that if resources are available (databases, time budget), the finest level of detail should be used when developing forest plans in order to produce the most accurate results in forest planning efforts.
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