Effect of Temperature on Acoustic Evaluation of Standing Trees and Logs: Part 2: Field Investigation
Keywords:Acoustic velocity, ambient temperature, logs, wood temperature, standing trees
AbstractThe objectives of this study were to investigate the effect of seasonal temperature changes on acoustic velocity measured on standing trees and green logs and to develop models for compensating temperature differences because acoustic measurements are performed in different climates and seasons. Field testing was conducted on 20 red pine (Pinus resinosa) trees and 10 freshly cut red pine logs at a 45-yr-old plantation stand in Arena, WI. Acoustic velocities of the red pine trees and logs and the ambient temperatures were monitored for 12 consecutive months. Results indicated that ambient temperature had a significant effect on acoustic velocities of trees and logs in winter when temperatures were below the freezing point. Acoustic velocities increased dramatically as ambient temperature dropped to below 0°C, but the increase became less significant when the temperature decreased to below -2.5°C. Above the freezing point, acoustic velocities were less sensitive to ambient temperature changes. From a practical standpoint, acoustic velocities of trees and logs measured at different climates and seasons can be adjusted to a standard temperature if measurements are conducted well above or well below freezing temperatures. However, measurements conducted around freezing temperatures could cause complications in making temperature adjustments. Users should avoid conducting field acoustic testing when wood temperature is around the freezing point.
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