Application Of Near-Infrared Spectroscopy To Determine The Juvenile-Mature Wood Transition In Black Spruce

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. In total, 127 wood samples were harvested from 50 sites located across the black spruce moss domain in the province of Quebec, Canada. Mechanical wood properties were determined by SilviScan. NIR spectra were collected on the transverse face of the samples. Good to excellent calibration statistics (R-2, 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 SilviScan data were compared with those obtained using NIRS predicted data. Using SilviScan 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 (-14.6/10.1). These results suggest that the transition age from juvenile to mature wood could be predicted by NIRS. This article makes some recommendations to improve method accuracy for operational use.