NIR detection of non-recoverable collapse in sawn boards of Eucalyptus globulus

NIR predictions of cellulose content and stiffness (modulus of elasticity, MOE) from spectra collected from the radial longitudinal surface of Eucalyptus globulus wood were found to be reliable indicators of zones of non-recoverable collapse associated with the presence of tension wood. Radial sections from 25 quarter-sawn boards cut from plantation-grown E. globulus trees in Spain were scanned to generate radial profiles of NIR-predicted wood properties at 2 mm increments. These boards manifested a range of non-recoverable collapse features, from no collapse to one or more severe collapse bands. Collapse bands occurred where NIR-predicted cellulose content and MOE exceeded threshold levels of 50 % and 25 GPa, respectively for more than four consecutive millimetres. A non-recoverable collapse indicator provided a clear predictor of non-recoverable collapse. A NRCI value ≥100 for a consecutive interval of at least 4 mm successfully predicted all ten NRC bands with shrinkage ≥10 % of board thickness. The potential applications of this tension wood detection method are discussed.