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When a log is sawn along the length, an outward bending or deflection of two half rounds arises from the release of growth stresses in the log. The relationship between this outward bending and the peripheral longitudinal growth strain in logs from a 10-year-old Eucalyptus nitens plantation was investigated. In total, 63 trees were felled and two logs (one bottom and an upper log) were cut from each felled tree. A strong association was observed between the measured longitudinal growth strain and the outward bending produced by splitting the log along its axis. A mathematical model was developed that enables calculation of the relationship between the surface axial growth stress and the opening of the split log. This involves calculation of the lateral deflection of a tapered cantilever beam of semi-circular cross-section under a known bending moment. The relationship between the opening of the slit log and the surface axial stress showed good agreement with the measured data on 126 logs. The model equation is effective in predicting the growth stress from the magnitude of the log distortion. This log sawing or splitting method is quick and reliable for assessing the surface growth stresses in small diameter trees. It could have potential in breeding programs for identifying families or clones for low-growth stresses of superior eucalypts for sawn timber production.

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The influence of inhomogeneity on acoustic velocity measured by a resonance-based WoodSpec acoustic tool and a transit-time-based Fakopp-2D tool was investigated. Four laminated panels with different degrees of inhomogeneity were prepared and acoustic velocities were measured using both tools. Velocities measured by the Fakopp-2D tool were always higher than those measured by the WoodSpec tool in all panels. The difference in the two velocities was found to vary depending on the magnitude of inhomogeneity. It was demonstrated that the velocity measured by the resonance frequency obeys the law of mixtures and is controlled by the volume-weighted average stiffness of the material. In contrast, the velocity measured by the Fakopp-2D tool was the velocity of the pulse that first reached the detector travelling at the dilatational speed.