香杉鼠害立木樹幹之腐朽率對超音波傳播時間的影響

本研究利用Pundit超音波儀器，測定香杉(Cunninghamia Konishii)鼠害立木樹幹之腐朽率，並以超音波傳播時間為基礎加以評估材質，結果顯示，藉由測定超音波穿透時間在樹幹徑向（在180及90度方向）的分析，立木樹幹的內部材質可以加以評估，直線迴歸統計顯示，隨著90度方向與徑向（180度）方向的穿透時間比率值增加，樹幹腐朽程度會降低；而傳播時間的增加率，隨樹幹腐朽量的增加而增大，此結果是比較於健康樹木在徑向的傳播時間為基準，以及測定樹幹在不同方位後的比率，作為腐朽程度的預測指標，這兩種指標證實立木樹幹存在的內部腐朽，可以藉由超音波徑向檢測加以評估。因此，基於同時在一個樹幹斷面上，使用轉換器檢測立木在不同方位多次後的超音波傳播時間，可以確定樹幹中可能缺點的存在及大小（定量）。

關鍵字

立木；超音波速度；傳播時間；穿透時間

並列摘要

Various degrees of wood decay in Luanta fir standing trees (Cunninghamia lancevlata var Konishii) damaged by squirrels were assessed. The propagation time of ultrasonic wave was measured using Pundit ultrasonic meter. Biological internal quality of standing trees could be evaluated by measuring the ultrasonic traversing time on the radial axis (in the 180 and 90° direction) of tree trunks. The ratio of traversing time in the 90° direction to radial (180°) direction tended to decrease with increased decay degree. However, the percentage of increase in transmission time tended to increase with increased decay degree. Results were compared with transmission times of healthy trees in the radial direction, and the ratio of transmission times in the different orientations as predictors of decay degree. The indicators verified that the internal decay of tree could be detected using ultrasonic measurement of the radial direction. Therefore, simultaneous measurement of the transmission time of ultrasonic wave by multiple transducers arranged around the stem in different orientations, the presence and size in the tree could be determined.

並列關鍵字

Standing tree ； Transmission time ； Traversing time ； Ultrasonic wave velocity

國際替代計量

香杉鼠害立木樹幹之腐朽率對超音波傳播時間的影響

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