非破壞性技術評估同齡級不同徑級紅檜及柳杉立木之材質

Abstract

相同樹齡的林木生長在同一地區的生育地時，經過數年後會有不同的胸高直徑表現(生長特性)，一般可區分為優勢木、中勢木、弱勢木等不同徑級的立木，本實驗是要選定同齡級卻不同徑級的紅檜，測其各種性質上之差異。先用非破壞性的方法預估材之優劣，待該紅檜經疏伐，製成小試材再進行材質評估，看看前後之結果是否有相關性。實際作法是先用Pilodyn用打孔深度測定立木表面之材質，再用超音波法作立木之檢測。製成無缺點之小試材，再以打音法、振動法測其性質，且行破壞性的抗壓強度、抗彎強度檢測。想要探討非破壞性試驗及破壞性試驗間的差異，以及利用非破壞性的方法評估立木材質之可行性。若瞭解相同樹齡不同徑級的材質特性，可以提供這些資訊給森林經營及利用者的參考依據。 結果顯示，同齡級的紅檜立木中，DBH大者，其性質越差。而在立木階段，可藉由超音波測試和Fractometer得知。小試材之MOR及抗壓強度。五項非破壞性檢測儀器中，結果類似。而非破壞檢測技術可以測出與破壞檢測技術類似的結果。 同齡級的柳杉立木中，超音波法不適合用於柳杉立木測量，用Pilodyn，及微破壞儀則可評估其性質，和胸徑成顯著負相關；各項非破壞測驗儀器試驗結果類似，小試材之性質可利用非破壞性檢測推估出。

The purpose of this study was to investigate the physics properties of Taiwan red cypress and Japanese cedar in the same age with different DBH(diameter at breast height) by using several nondestructive testing methods. The methods included ultrasonic wave method, Pilodyn method, stress wave method, tap tone method, soft x-ray, compression stress and bending test. First of all, standing tree was evaluated by ultrasonic wave method and Pilodyn.. Then, they was felled and cut into small clear specimens, and evaluated physics properties by nondestructive tests. Finally, the bending strength test and compression stress test was carried. This study was also to figure out the difference of the physics properties between standing trees and small specimens, and hope to know relationship between the nondestructive tests results and mechanical strength. Statistical results showed there are significantly relationships between non- destructive tests and destructive tests. The physics properties of Taiwan red cypress and Japanese cedar decreased with DBH increasing. There are also significantly relationships among all the non-destructive tests. Taiwan red cypress standing tree could be evaluated by Fractometer and ultrasonic-wave method with better prediction. While the Japanese cedar standing tree could be evaluated by using Pilodyn method and Fractometer with better results.