微破壞儀非破壞性評估不同疏伐及修枝處理對台灣杉立木壓縮強度的影響

Nondestructive Evaluation of Crushing Strength of Young Taiwania Trees Grown under Different Thinning and Pruning Treatments Using a Fractometer

林振榮(Cheng-Jung Lin) ； 邱志明(Chih-Ming Chiu) ； 王瀛生(Ying-Sheng Wang) ； 郭博文(Po-Wen Kuo) ； 莊鴻濱(Horng-Bin Chung)

《台灣林業科學》 20卷2期 (2005/06) Pp. 105-112

https://doi.org/10.7075/TJFS.200506.0105

摘要

本研究目的在利用微破壞儀(fractometer)，以非破壞性方式，探討以樹芯為材料時，評估幼齡台灣杉(Taiwania cryptomerioides Hay)立木不同疏伐及修枝處理，對壓縮強度的影響。結果顯示，平均壓縮強度在不同疏伐處理中，依無疏伐、中度疏伐、及強度疏伐處理次序遞減；而在不同修枝處理中，則依中度修枝、無修枝、及強度修枝處理次序遞減，無疏伐及中度修枝處理的樹木，具有較高的壓縮強度，經進一步的統計分析結果得知，大部份處理其間沒有顯著差異性存在。平均壓縮強度在樹幹徑向的變異，由髓心向樹皮側首先緩慢的降低約至3.6cm處後，再逐漸增加至距髓心12.6cm處，最後再緩降至樹皮側。整體而言，壓縮強度隨著離髓心距的增加，向樹皮側方向逐漸增加，文中並討論一些使用微破壞儀檢測壓縮強度時的實務經驗。

關鍵字

台灣杉 ； 壓縮強度 ； 樹芯 ； 疏伐 ； 修枝

並列摘要

The effects of different thinning and pruning methods on the crushing strength of young Taiwania trees (Taiwania cryptomerioides Hay) using a fractormeter were investigated. The method of study was to explore the crushing strength of incremental cores as an alternate nondestructive testing method. The average crushing strength in the thinning treatments revealed the trend of no thinning＞medium thinning＞heavy thinning, indicating that thinning reduced the average compressive strength. The average compressive strength in the pruning treatments showed the following trend: medium pruning＞no pruning＞heavy pruning. A better average compressive strength of trees was obtained from wood subjected to no thinning and medium pruning treatments. However, most results showed no statistically significant differences among thinning and pruning treatments. Transverse variations in the average crushing strength decreased from the pith outwards to 3.6cm, and then gradually increased to 12.6cm. Finally, strength showed a gradual decrease toward the bark. Generally speaking, the average crushing strength increased linearly with increasing distance from pith by linear regression. Observations of testing incremental core specimens and its validity are discussed in this study.

並列關鍵字

Taiwania ； compressive strength ； increment core ； thinning ； pruning