Variations in acoustic velocity and density with age, and their interrelationships in radiata pine

Acoustic velocity by the Fakopp time of flight (ToF) tool was used to estimate outerwood stiffness of trees within stands and between stands of different age classes (ages 8, 16 and 25). The TOF acoustic velocity measured in the standing trees was generally higher than the acoustic velocity measured by the Hitman (resonance) tool on the associated logs. The difference between the two velocities tended to be greater in the older and large diameter trees. The large variability in acoustic velocity, or preferably V2, makes it an efficient wood quality variable for screening trees.Wood density variables did not exhibit any relationship with acoustic velocity or modulus of elasticity (MoE) within each age-class. The classic pseudo-relationship observed with pooled data from all stand ages is mainly due to a stand age-effect and so one should be cautious in relying on any significant association between density and MoE.