The relationship between standing tree acoustic assessment and timber quality in Scots pine and the practical implications for assessing timber quality from naturally regenerated stands

This paper describes studies that were conducted to test the hypotheses that acoustic tools provide reliable non-destructive predictions of mechanical properties of Scots pine (Pinus sylvestris L.) and that these allow comparisons of the timber quality between stands with different silvicultural histories. Acoustic testing was carried out in two plantations (Mount High and Seafield Estate) and one naturally regenerated stand (Glengarry Forest) in North Scotland. One hundred trees were assessed at Mount High and Seafield Estate and 11 trees were felled for cutting into 40 small clear specimens. These were then subjected to static three-point bending tests. Linear regression analysis demonstrated a good correlation between acoustic velocity and modulus of elasticity (MoE) (R² = 0.53) and between acoustic velocity and modulus of rupture (MoR) (R² = 0.59). A non-linear model was applied to take into account the effect of age on MoE (R² = 0.58) and MoR (R² = 0.54), and the data from all three sites were compared taking into account the biases that could be attributable to differences in age. The predicted mean MoE and MoR values indicated that the mechanical properties of the clear wood from the naturally regenerated trees are at least comparable with those from the plantation-grown trees.