Measurement results on the identification of red hearts of European beech (Fagus sylvatica L.) with the drill devices Teredo and Resistograph 1410 and also the impulse hammer sound system IML

Title of the paper: Measurement results on the identification of red hearts of European beech (Fagus sylvatica L.) with the drill devices Teredo and R esistograph 1410 and also the impulse hammer sound system IML. a) The mean radial sound velocities of the different red heart types did no t significantly differ. The values layed in the range of normal "white colo ured" beech wood (1100 m/s to 1500 m/s). Gray heart wood showed lower veloc ities (972 m/s). Also the tangential velocities were 100 m/s to 200 m/s low er than of normal wood. The IML-sound system is not suitable for detecting red hearts of beech boles. b) Both Teredo and Resistograph system are unsuitable for detecting red hea rts in beech stems (Fig. 6 to 9). c) The draw back curves of the Teredo system are problematic because not ca lculable systematic errors can occur. Therefore they should not be used for wood resistance interpretations (Fig. 6, 12). d) Measurements on frozen woods are impossible using the Teredo but not the resistograph system. The resistograph has problems with dense woods becaus e of the impossibility drilling in and clamping the drilling needle. e) Diminished wood resistances such as central rotten wood and holes on bee ch could be exactly detected by the Teredo and Resistograph curves.