Main mechanical properties of new Chinese fir clones and their rapid prediction by near-infrared spectroscopy

Abstract

Owing to its rapidity and accuracy, near-infrared (NIR) spectroscopy is a powerful tool to establish appropriate prediction models with an innovative method to evaluate wood properties. To reveal the mechanical qualities of clonal Chinese fir woods and to determine sound prediction models of mechanical properties, four main mechanical properties of six Chinese fir clones (Yang 020, Yang 061, Kaihua 3, Kaihua 13, Daba 8, Kailin 24) were evaluated by NIR spectroscopy. The clones Kaihua 13, Kailin 24, and Yang 020 showed good mechanical properties. To estimate mechanical properties with NIR spectroscopy, different methods should be adopted for different properties. The average spectra of radial and tangential sections combined with multiple scattering correction (MSC) and Savitzky–Golay (S–G) smoothing methods were used to predict the modulus of rupture and modulus of elasticity. By adopting cross section spectra and taking MSC and S–G smoothing methods for pretreatment, the models of compressive strength parallel to grain could deliver the best results. For wood hardness, the models established with average spectra of three sections and first-derivative method were preferred. The correlation coefficients of the prediction models were between 0.84 and 0.90, and those of the calibration models were between 0.75 and 0.96.