Acoustic evaluation of Alaskan young-growth wood
Author: Wang, Xiping; Ross, Robert J.
Source: Proceedings of the 15th International Symposium on Nondestructive Testing of Wood : Sept. 10-12, 2007. Madison, WI : Forest Products Society, c2008: pages 97-105.
With the move to intensive forest management to meet wood demand and to preserve the environment, southeast Alaska is experiencing a period of significant change in terms of wood characteristics or wood quality. In order to responsibly manage the young-growth stands, it is important to evaluate tree quality prior to harvest and understand the product and economic potential of the wood fiber in standing trees. The research reported in this paper is a component of a larger wood quality project that was designed to address the quality concerns on the young-growth wood in southeast Alaska and grade issues regarding silvicultural treatments. The objectives of this sub-study were to investigate the applicability of a newly developed acoustic wave method for assessing wood properties of standing, young-growth western hemlock and Sitka spruce trees and to determine if the effects of pre-commercial thinning and commercial thinning on wood quality could be properly identified with this acoustic evaluation technique. Four hundred and sixty-one standing trees from nine different sites were nondestructively tested using a time-of-flight acoustic wave technique. The study sites reflected different age classes, ranging from 37 to 73 years old, and represented a range of pre-commercial thinning and commercial thinning spacings. Sample trees were subsequently harvested, sawn into logs, and then processed into structural lumber. The acoustic velocities of all mill-length logs were obtained using a resonance acoustic tool. Full-size lumbers recovered from the logs were E-rated using a transverse vibration method and then mechanically tested to failure for stiffness and strength properties. This paper only reports the results from tree-log data analysis. Acoustic data of the trees and corresponding logs were analyzed on both individual tree levels and stand levels to examine the effects of tree diameter at breast height, stand age, and thinning regime on tree acoustic velocity.
Keywords: Bending, elasticity, spruce, mechanical properties, wood properties, Alaska, Sitka spruce, western hemlock, stress waves, hemlock, grading, nondestructive testing, defects, acoustic properties, acoustic imaging, deterioration, wood quality, bending strength, stiffness, logs, stand denstiy, thinnings, small timbers, utilization, small-diameter timber, smallwood, standing trees, wood decay
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Wang, Xiping; Ross, Robert J. 2008. Acoustic evaluation of Alaskan young-growth wood. Proceedings of the 15th international symposium on nondestructive testing of wood. 2007 September 10-12: Duluth, MN: 97-105.
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