doi: 10.1093/wjaf/13.4.z5pmid: N/A
Article PDF first page preview Close This content is only available as a PDF. © 1998 by the Society of American Foresters
doi: 10.1093/wjaf/13.4.z1pmid: N/A
Article PDF first page preview Close This content is only available as a PDF. © 1998 by the Society of American Foresters
Martin, Fred, C.;Flewelling, James, W.
doi: 10.1093/wjaf/13.4.109pmid: N/A
Abstract The study appraised nine models that predict total tree height from diameter by species within individual stands. Models were fitted with nonlinear least squares by species within individual stands using inventory data from western Washington. Stand-level models were examined with respect to species, geographic regions, dominance characteristics, and sample sizes. Models were evaluated for mean square error, bias by diameter class, overfitting, and consistency in relative ranking. No substantial differences in model performance were noted with respect to geographic regions, but small differences were evident by species, dominance characteristics, and sample sizes. Model bias occurred with some but not all models. Overfitting was detected and considered a problem in fitting three-parameter models with the often small height sample in some stands. Some models were consistently good across species and sample sizes, whereas others were consistently poor. Yet the performance of other models varied by species and sample sizes. For predicting heights by species within individual stands, a single model was recommended Height = 1.37 + b0eb1dbh-1.0 A method was examined for constraining height predictions for trees beyond the range of sample data. West. J. Appl. For. 13(4):109-119. This content is only available as a PDF. © 1998 by the Society of American Foresters
Amaranthus, Michael, P.;Weigand, James, F.;Abbott,, Rick
doi: 10.1093/wjaf/13.4.120pmid: N/A
Abstract In the Pacific Northwest, nontimber forest products account for more than $200 million in annual revenue yet there is little intentional management to promote the dozens of these harvested species. In the southern Cascade Range in Oregon, management experiments are being installed to develop and refine silvicultural practices that increase financial returns from high-elevation stands. Pretreatment measurements are complete, and harvest treatments will begin in 1998. The harvest treatments will emphasize the most valuable products: high-quality timber, American matsutake mushrooms (Tricholoma magnivelare), and other nontimber forest products such as food-flavoring extracts, decorative boughs, Christmas trees, and pine cones. Management practices will adjust species composition, remove disease and infested trees, prune target species, manage for timber on long rotations, and opportunistically manage and harvest nontimber forest products, especially the highly valued American matsutake. A comprehensive monitoring program will track ecosystem and economic variables at different temporal scales. In this paper we present management scenarios that emphasize forest function and biological diversity while providing an even flow of commercially valuable timber and nontimber forest products. West. J. Appl. For. 13(4):120-128. This content is only available as a PDF. © 1998 by the Society of American Foresters
Gebert, Krista, M.;Niccolucci, Michael, J.;Schuster, Ervin, G.
doi: 10.1093/wjaf/13.4.129pmid: N/A
Abstract Given the complex and expensive nature of timber sale planning, timber offerings that receive no bids waste valuable time and resources for the managers of national forests. This article compares several tools for predicting the salability of timber offerings. These tools include probability-based techniques and appraisal-based techniques. The probability-based techniques include probit regression and discriminant analysis. The appraisal-based techniques use various modifications of the standard transaction evidence appraisal equations to predict salability. Results show probability-based techniques do better at correctly classifying timber offerings as sold or unsold. They correctly classify nearly 100% of the sold offerings, which constitute most of the offerings in the sample. However, if the user's primary interest is to predict unsold offerings correctly, appraisal-based techniques outperform probability-based techniques. West. J. Appl. For. 13(4):129-136. This content is only available as a PDF. © 1998 by the Society of American Foresters
Randall,, William;Johnson, G., R.
doi: 10.1093/wjaf/13.4.137pmid: N/A
Abstract Survival and third-year height were examined on 2,383 reforestation units from 1983 to 1994 to determine which factors impact reforestation success. Survival of Douglas-fir (Pseudotsuga menziesii) varied by as much as 20% from year to year. The most significant factor affecting reforestation success was the nursery that provided the seedlings. Nursery impacted both survival and height of Douglas-fir and impacted height for noble fir (Abies procera) and white pine (Pinus monticola). No nursery was best for all species. Other factors that were important for all three species were the administrative unit where the seedlings were planted, initial plant height, aspect, and length of storage prior to planting. Other significant factors that were important for Douglas-fir were seed origin, planting month, protection, stock type, and aspect. For noble fir, other important factors were planting month and stock type; for white pine, the other important factor was slope. Elevation of the seed source and the planting unit affected Douglas-fir survival and height but did not affect the other two species. This supports the smaller elevational bands for Douglas-fir compared with noble fir and white pine. West. J. Appl. For. 13(4):137-143. This content is only available as a PDF. © 1998 by the Society of American Foresters
doi: 10.1093/wjaf/13.4.144pmid: N/A
Article PDF first page preview Close This content is only available as a PDF. © 1998 by the Society of American Foresters
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