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Growth and yield of western larch under controlled levels of stocking in the Blue Mountains of Oregon.Author(s): P.H. Cochran; K.W. Seidel
Source: Res. Pap. PNW-RP-517. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p
Publication Series: Research Paper (RP)
Station: Pacific Northwest Research Station
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DescriptionRepeated thinning to five growing-stock levels resulted in widely differing tree sizes and volumes per acre after 30 years. Largest trees but the least cubic-volume yield per acre were produced in the heaviest thinning level, whereas highest board-foot yields were found in intermediate thinning levels. Partial defoliation by larch casebearer (Coleophora laricella Hübner), drought, and top damage from ice occurred, and site trees grew less in height than expected during the 30-year study. Curvilinear increases in periodic annual increments of both basal area and cubic volume generally occurred with increasing stand density, but increments dropped off at the highest stand densities for some periods. Anticipated patterns for these increments were found after fitting a model that included stand density index, height increments of site trees, and dummy variables for periods as independent variables. Heavy thinning did not increase the age of culmination of cubic-volume mean annual increment as expected. Thinning stands of larch to densities as low as 50 percent of "normal" results in little loss of basal-area growth, a moderate loss in volume production, and a large increase in tree diameter. Thinning is necessary in many larch stands to maintain vigorous, rapidly growing trees. Thinning levels will greatly affect the appearance of future stands.
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CitationCochran, P.H.; Seidel, K.W. 1999. Growth and yield of western larch under controlled levels of stocking in the Blue Mountains of Oregon. Res. Pap. PNW-RP-517. Portland, OR: U.S. Department of Agriculture, Forest Service, Pacific Northwest Research Station. 35 p
KeywordsStocking levels, bole area, stand density index, growth, yield, larch case-bearer, ice damage, future stands
- Growth of western larch after thinning from above and below to several density levels: 10-year results.
- Growth and yield of western larch in response to several density levels and two thinning methods: 15-year results.
- Larch Casebearer in Western Larch
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