Influence of thinning on acoustic velocity of Douglas-fir trees in western Washington and western Oregon
Author: Briggs, David G.; Thienel, Gonzalo; Turnblom, Eric C.; Lowell, Eini; Dykstra, Dennis; Ross, Robert J.; Wang, Xiping; Carter, Peter.
Source: Proceedings of the 15th International Symposium on Nondestructive Testing of Wood, Sept. 10-12, 2007. Madison, WI : Forest Products Society, c2008: pages 113-123.
Acoustic velocity was measured with a time-of-flight method on approximately 50 trees in each of five plots from four test sites of a Douglas-fir (Pseudostuga menziesii (Mirb.) Franco) thinning trial. The test sites reflect two age classes, 33 to 35 and 48 to 50 years, with 50-year site index ranging from 35 to 50 m. The acoustic velocity distribution in each plot formed the basis for selecting a stratified sample of 12 trees that were harvested for conversion into veneer or lumber. Using a resonance acoustic method, acoustic velocity was obtained for the delimbed and topped merchantable stem. The merchantable stem was bucked into long logs that were either mostly 35 ft (10.7 m) long for veneer conversion or 33 ft (10.1 m) long for lumber conversion. After delivery to mill log yards, the long logs were measured with the resonance acoustic velocity method. The veneer long logs were bucked into 17 ft (5.1) short logs and the lumber long logs were bucked into 16 ft (4.9 m) short logs. The short logs were then tested with the resonance acoustic velocity method and cross-sectional discs were removed for measurement of density, moisture content, and other properties. Full and half sheets of veneer and 2 by 4 and 2 by 6 lumber recovered from the short logs were tested for stiffness and other properties. This paper presents two analyses. First, the 50 tree per plot sample is summarized and regression models are developed to examine the effects of thinning, stand age, stand density, and site index on tree acoustic velocity. Second, the six sample trees from each plot that were converted to lumber are summarized to examine relationships between time-of-flight acoustic velocity measured on the standing tree, the resonance acoustic velocity measured on the first woods log and first short log, and the modulus of elasticity (MOE) of lumber obtained from the first short log.
Keywords: Modulus of elasticity, elasticity, veneers, veneering, wood density, wood anatomy, trees, mechanical properties, Douglas fir, nondestructive testing, acoustic properties, grading, acoustic properties, wood quality, site index, Oregon, Washington, forest thinning, stiffness, logs, smallwood, small timbers, stand density, wood quality, acoustic testing, acoustic velocity, standing trees
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Briggs, David G.; Thienel, Gonzalo; Turnblom, Eric C.; Lowell, Eini; Dykstra, Dennis; Ross, Robert J.; Wang, Xiping; Carter, Peter. 2008. Influence of thinning on acoustic velocity of douglas-fir trees in western Washington and western Oregon. Proceedings of the 15th international symposium on nondestructive testing of wood. 2007 September 10-12: Duluth, MN: 113-123.
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