天然林牛樟機械性質變異與未成熟材境界之探討

Study on the Variation of Mechanical Properties and Juvenile Wood Region of Natural Stout Camphor Trees

邱志明(Chih-Ming Chiu) ； 林振榮(Cheng-Jung Lin)

《林產工業》 19卷2期 (2000/06) Pp. 183-194

https://doi.org/10.6561/FPI.2000.19(2).4

摘要

本試驗取自林試所六龜分所多納林區24林班之3株天然林樣木，取樣部位高度0.5~1.5 m、直徑為78~106 cm、樹齡皆超過100年以上。其氣乾比重(r_u)變化範圍由0.424~0.598，平均0.508，MOR為353~1290 kgf/cm^2，平均803 kgf/cm^2，MOE由21598~132592 kgf/cm^2，平均69265 kgf/cm^2，縱向壓縮強度(σ_c)，87~469 kgf/cm^2，平均328 kgf/cm^2，縱向壓縮彈性係數(E_c)，3790~36028 kgf/cm^2，平均20027 kgf/cm^2，由此可知其機械性質變異甚大，其中以E_c變異最大，最大最小差距達到10倍；最小為r_u，最大和最小差異僅1.4倍。其3株樣木，各強度性質間關係極顯著，又由牛樟機械性質在橫向變化，由分段迴歸分析方法，得知其未成熟材境界為距髓心距離約10 cm，林齡約為20-25年。

關鍵字

牛樟天然林 ； 機械強度 ； 未成熟材

並列摘要

Three stout camphor (Cinnamomum kanehirae) trees were obtained from natural forest at compartment No.24, To-Na working district in Lu-Kuei Experimental Forest. Samples were taken at tree height of 0.5-1.5 m, and the diameters ranged from 78 to 106 cm. The tree ages were all beyond one hundred years old. The mean value and the range of r_u, MaR, MOE, σ_c and E_c were 0.508 (0.424~0.598) ,803 (353~290) kgf/cm^2, 69265 (21598~132592) kgf/cm^2, 328 (87~469) kgf/cm^2 and 20027(3790~36028) kgf/cm^2, respectively. From the above data we found that there were great variations in different mechanical properties of stout camphor trees. Among the mechanical properties, the biggest variation was found in E_c, i.e., the maximum value was 10 times that of the minimum. The smallest variation was found in r_u, the difference between the maximum and the minimum was only 1.4 times. The relationships among different mechanical properties were very significant. Since there was a definite tendency of mechanical strengths in the cross section of stem, the segmented regression analysis for mechanical properties in the radial direction can be used to distinguish juvenile wood and mature wood region. The results showed that the juvenile wood region was about 10 cm away from the pith and was about 20~25-yr-old.

並列關鍵字

Cinnamomum kanehirae ； Mechanical properties ； Juvenile wood region