论文信息 - Ultrasonic Acoustic Emissions from the Sapwood of Thuja occidentalis Measured inside a Pressure Bomb.

Ultrasonic Acoustic Emissions from the Sapwood of Thuja occidentalis Measured inside a Pressure Bomb.

An improved method of counting acoustic emission (AE) events from water-stressed stems of cedar (Thuja occidentalis L.) is presented. Amplified AEs are analyzed on a real time basis by a microcomputer. The instrumentation counts AE events in a fashion nearly analogous to scintillation counting of radioactive materials.The technique was applied to measuring ultrasonic AEs from the stems of cedar inside a pressure bomb. The shoots were originally fully hydrated. When the shoots are dehydrated in the bomb by application of an overpressure very few AEs were detected. When the bomb pressure is reduced after dehydration of the shoot, AE events could be detected. We conclude that ultrasonic AEs are caused by cavitation events (= structural breakdown of water columns in the tracheids of cedar) and not by the breaking of cellulose fibers in the wood.

[1] M. Tyree,et al. A comparison of systematic errors between the Richards and Hammel methods of measuring tissue – water relations parameters , 1978 .

[2] M. Tyree,et al. Cavitation Events in Thuja occidentalis L.? : Utrasonic Acoustic Emissions from the Sapwood Can Be Measured. , 1983, Plant physiology.