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    Author(s): Fenglu Liu; Pengfei Xu; Houjiang Zhang; Cheng Guan; Dan Feng; Xiping Wang
    Date: 2019
    Source: Forests. 10(8). 17 p.
    Publication Series: Scientific Journal (JRNL)
    Station: Forest Products Laboratory
    PDF: Download Publication  (2.0 MB)


    In this study, 145 poplar (Populus × euramericana cv.’74/76’) seedlings, a common plantation tree species in China, were selected and their ultrasonic velocities were measured at four timepoints during the frst growth year. After that, 60 poplar seedlings were randomly selected and cut down to determine their acoustic velocity, using the acoustic resonance method. The effects of infuencing factors such as wood green density, microfbril angle, growth days, and root-collar diameter on acoustic speed in seedlings and the relationship between ultrasonic speed and acoustic resonance speed were investigated and analyzed in this work. The number of specimens used for investigating growth days and root-collar diameter was 145 in both cases, while 60 and two specimens were used for investigating wood density and the microfbril angle, respectively. The results of this study showed that the ultrasonic speed of poplar seedlings signifcantly and linearly increased with growth days, within 209 growing days. The ultrasonic velocity of poplar seedlings has a high and positive correlation with growth days, and the correlation was 0.99. However, no signifcant relationship was found between the ultrasonic velocity and root-collar diameter of poplar seedlings. Furthermore, a low and negative relationship was found between wood density and ultrasonic speed (R2 = 0.26). However, ultrasonic velocity signifcantly decreased with increasing microfbril angle (MFA) in two seedlings, and thus MFA may have an impact on ultrasonic speed in poplar seedlings. In addition, ultrasonic velocity was found to have a strong correlation with acoustic resonance velocity (R2 = 0.81) and a good correlation, R2 = 0.75, was also found between the dynamic moduli of elasticity from ultrasonic and acoustic resonance tests. The results of this study indicate that the ultrasonic technique can possibly be used to measure the ultrasound speed of young seedlings, and thus early screen seedlings for their stiffness properties in the future.

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    Liu, Fenglu; Xu, Pengfei; Zhang, Houjiang; Guan, Cheng; Feng, Dan; Wang, Xiping. 2019. Use of time-of-flight ultrasound to measure wave speed in poplar seedlings. Forests. 10(8). 17 p.


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    Ultrasonic speed, poplar seedlings, acoustic resonance, density, microfibril angle, root-collar diameter

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