Assessing the within-tree variation in stiffness from ultrasonic velocity and specific gravity measurements in Douglas-fir and loblolly pine

  • Authors: Dahlen, Joseph; Auty, David; Eberhardt, Thomas L.; Turnblom, Eric; Lowell, Eini; Schimleck, Laurence; Montes, Cristian
  • Publication Year: 2019
  • Publication Series: Paper (invited, offered, keynote)
  • Source: Gen. Tech. Rep. FPL-GTR-272. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory: 122-131.

Abstract

Roundwood is increasingly sourced from highly productive plantations that yield excellent growth. Information is needed on the wood properties from plantations because these trees will contain a higher proportion of low stiffness corewood compared to naturally regenerated trees of the same size. The objective of this study was to examine the within-tree variation in stiffness for Douglas-fir and loblolly pine grown in the United States through assessment of specific gravity (SG) and ultrasonic velocity (USV). Approximately 500 pith-to-bark radial strips collected from multiple height levels from each species were processed via a book-matched technique to yield a 2 mm tall (longitudinal) SG sample and an 8.5 mm tall USV sample. Ring-by-ring SG was measured using x-ray densitometry. Time-of-flight USV was measured in the longitudinal direction at 10 mm radial resolution using two 1-MHz delay line transducers with the distance between the two transducers measured at each radial location using a LVDT sensor. Patterns of USV followed the asymptotic patterns similar to the inverse of microfibril angle both radially and by height level. For Douglas-fir, radially at the pith and vertically at the stump, USV values averaged 3,750 m/s whereas at upper height levels at the pith USV values averaged 4,250 m/s. At the stump, USV reached asymptote values at 25 years compared to 15 years for other height levels. This presentation will focus primarily on the measurement of the USV and the relationships discussed between USV with SG, tracheid length and microfibril angle.

  • Citation: Dahlen, Joseph; Auty, David; Eberhardt, Thomas L.; Turnblom, Eric; Lowell, Eini; Schimleck, Laurence; Montes, Cristian. 2019. Assessing the within-tree variation in stiffness from ultrasonic velocity and specific gravity measurements in Douglas-fir and loblolly pine. In: Wang, X.; Sauter, U.H.; Ross, R.J., eds. Proceedings: 21st International Nondestructive Testing and Evaluation of Wood Symposium. Gen. Tech. Rep.  FPL-GTR-272. Madison, WI: U.S. Department of Agriculture, Forest Service, Forest Products Laboratory: 122-131.
  • Keywords: acoustic velocity, nondestructive testing, Pinus taeda, Pseudotsuga menziesii, wood and fiber quality
  • Posted Date: December 9, 2019
  • Modified Date: September 23, 2020
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    Publication Notes

    • This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
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