Relationship between Stress-Wave Velocity of Standing Tree and Wood Quality in 27-Year-Old Hinoki (Chamaecyparis obtusa Endl.)

In the present study, to clarify the relationship between stress-wave velocity of standing trees and their wood quality, stress-wave velocity of 122 standing trees in 27-year-old Hinoki (Chamaecyparis obtusa Endle.) plantation were measured by using a commercial hand held stress-wave timer (FAKOPP). Ten trees were cut down for examining the anatomical properties, static bending properties of small-clear specimen, and quality of square timber (1700 by 55 by 55mm). Stress-wave velocity of standing trees appeared to be affected by wood quality, especially by basic density and Young's modulus in juvenile wood. Significant relationships between stress-wave velocity of standing trees and dynamic Young's modulus or modulus of elasticity in static bending of square timber were found. However, it was very difficult to evaluate the modulus of rupture in static bending of square timber by stress-wave velocity of standing trees, because square timber had some defects such as knots. These results suggested that modulus of elasticity in static bending of square timber can be predicted by the stress-wave velocity.