Canadian Forest Service Publications
Application of near infrared spectroscopy to determine the juvenile-mature wood transition in black spruce. 2015. Giroud, G.; Defo, M.; Bégin, J.; Ung, C.-H. For. Prod. J. 65:129-138.
Issued by: Laurentian Forestry Centre
Catalog ID: 36078
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The potential of near-infrared spectroscopy (NIRS) to determine the transition from juvenile to mature wood in black spruce (Picea mariana (Mill.) B.S.P.) was assessed. A total of 127 wood samples were harvested from 50 sites located across the black spruce-moss domain in the province of Québec, Canada. Mechanical wood properties were determined by SilviScanTM. FT-NIR spectra were collected on the transverse face of the samples. Good to excellent calibration statistics (R², ratio of performance to deviation) were obtained for basic density (0.85, 1.8), microfibril angle (0.79, 2.2) and modulus of elasticity (0.88, 2.9). Two-segment linear regressions were applied to microfibril angle profiles to determine the transition age and then calculate the juvenile and mature wood properties. The values obtained using SilviScanTM data were compared with those obtained using NIRS predicted data. Using SilviScanTM data, the average transition age was 23 years, with a standard deviation of 7 years. The correlation was moderate for the transition age (r=0.592, P<0.0001), which was slightly underestimated by NIRS with a mean prediction error (and 95% limits of agreement) of -2.2 ± 6.3 years (10.1/-14.6). These results suggest that the transition age from juvenile to mature wood could be predicted by NIRS. This paper makes some recommendations to improve method accuracy for operational use.
Plain Language Summary
In this study, the researchers were able to verify that infrared spectroscopy (IRS) can be used to predict the mechanical properties of black spruce wood.
This inexpensive, non destructive method can be used to assess wood quality during forest inventories based on samples collected from standing trees. It can also be used to detect the proportion of juvenile wood in relation to mature wood. Juvenile wood is usually less dense and has less mechanical strength, both of which are important properties for the sawn lumber and pulp and paper industry.
Juvenile wood forms during the first years of tree growth. Later, the structure of the wood produced by the tree changes and that wood is called mature wood. Since it is difficult to determine how many years will pass before the tree begins to produce mature wood, a tool was needed to determine when the transition between juvenile and mature wood occurs.