- 期刊
超音波徑向檢測評估不同疏伐修枝處理對台灣杉立木材質之影響
Evaluation of Wood Quality of Taiwania Standing Trees Grown wih Different Thinning and Pruning Treatments Using the Radial Ultrasonic-wave Method
摘要
本篇報告的目的在利用超音波檢測不同疏伐及修枝處理對台灣移徑向材質的影響，結果在立木徑向超音波速度為1763 m/s~1808 m/s，而動彈性係數為16901 kgf/cm^2~19189 kgf/cm^2，而氣乾試材徑向超音波速度範圈為2194 m/s~2354 m/s，而動彈性係數為18782 kgf/cm^2~23622 kgf/cm^2。無疏伐及中度修枝處理的台灣特立木有較高的徑向超音波速度及動彈性係數，而氣乾試材時則以中度疏伐及中度修枝處理較高。另外，立木徑向超音波遠度及動彈性係數較低於氣乾試材者，主要原因是受立木狀態時有較高含水率的影響。不同疏伐處理間徑向試材的平均氣乾密度，其大小依序為無疏伐處理＞中度疏伐＞強度疏伐，疏伐處理有減低平均年輪密度的趨勢。而不同修枝處理間，其大小依序為中度修枝＞無修枝＞強度修枝。立木的動彈性係數隨著氣乾試材動彈性係數的增加而增加，兩者間的關係可以荳線迴歸式表示，但其決定係數值偏低口徑向及縱向試材的超音波連度與動彈性係數並沒有一致的傾向。
並列摘要
The effects of different thinning and pruning methods on the ultrasonic velocity and dynamic modulus of elasticity in radial direction were examined for Taiwania trees and specimens using ultrasonic-wave method. The radial ultrasonic wave velocity varies from l763m/s to l808m/s for standing tree, 2l94m/s to 2354m/s for air-dried specimen. The radial dynamic modulus of elasticity varies from 16901 kgf/cm^2 to 19189 kgf/cm^2 for standing tree, 18782 kgf/cm^2 to 23622kgf/cm^2 for air-dried specimen. The higher radial ultrasonic wave velocity and dynamic modulus of elasticity of Taiwania trees occurred in the no-thinning and medium pruning treatment; those of air-dried specimens occurred in the medium thinning and medium pruning treatment. Moreover, the average values of radial ultrasonic wave velocity and dynamic modulus of elasticity of specimens were greater than those of standing trees due to an increase in the moisture content at trunks. The average wood density after the thinning treatments showed a trend as follows: no thinning＞ medium＞heavy. This indicates that thinning reduces the average ring density. The average wood density after the pruning treatments showed a trend as follows: medium＞ no pruning＞heavy. The values of dynamic modulus of elasticity of standing tree increased with increases of those of air-dried specimen, but the coefficient of determination was lower. The average radial ultrasonic wave velocity and dynamic modulus of elasticity of standing trees are different from air-dried specimens.