Abstract: Use of a single end testing of stems of felled trees whereby by inducing a sonic wave with an impact and by reference to detected reflections and with a knowledge of the length of the stem the stiffness and/or strength characteristics of the stem or logs to be cut therefrom can be derived. A preferred procedure is a determination of the fundamental frequency f0 which relates to velocity V, the speed of longitudinal compressional motions along the stem, and L, the length of the stem, as follows: V=2Lf0. From that value V or a function of V can be derived an indicator of stiffness and/or strength.

Abstract: The present invention relates to the use of a single end testing of stems of felled trees whereby by inducing a sonic wave with an impact and by reference to detected reflections and with a knowledge of the length of the stem the stiffness and/or strength characteristics of the stem or logs to be cut therefrom can be derived. A preferred procedure is a determination of the fundamental frequency f0 which relates to velocity V, the speed of longitudinal compressional motions along the stem, and L, the length of the stem, as follows: V=2Lf0. From that value V or a function of V can be derived an indicator of stiffness and/or strength. For example the modulus of elasticity (MOE) is such an indicator and can be determined by the equation MOE=&rgr; V2 where &rgr; is density. For green felled timber &rgr; can be estimated as approximating 1000 kg/m3.