30年生國產大葉桃花心木造林木之生長輪特徵及木纖維長度變異

Variations of Growth Ring Characteristics and Wood Fiber Length of 30-year-old Domestic Plantation Big-leaf Mahogany

卓志隆(Chih-Lung Cho) ； 張婕瑜(Chieh-Yu Chang)

《林產工業》 33卷2期 (2014/06) Pp. 71-78

https://doi.org/10.6561/FPI.2014.33(2).2

摘要

本研究旨在探討30年生國產大葉桃花心木（Swietenia macrophylla）造林木之生長輪特徵及木纖維細胞長度之變異。試驗結果顯示生長輪密度在3個徑向階段間（距髓心第1－8、9－21及22－26個生長輪數）與不同樹高間皆存在顯著差異性，生長輪密度沿徑向由髓心至樹皮呈降低趨勢；由樹木基部至樹梢呈緩和增加趨勢。生長輪寬度與早材寬度有高度相關關係，早材密度、晚材密度及晚材率為決定生長輪密度之主要因子。生長輪寬度與生長輪密度間呈低相關關係，表示大葉桃花心木造林木年間生長快慢對於木材密度不會有顯著的影響，木纖維細胞長度由髓心至樹皮呈顯著性的增長；由樹木基部至樹梢則呈顯著性降低。依木纖維細胞長度伸長率1%以下時，作為未成熟材與成熟材境界決定結果，大葉桃花心木造林木之平均未成熟材位置為距髓心第20個生長輪。

關鍵字

大葉桃花心木造林木 ； 生長輪特徵值 ； 木纖維長度 ； 未成熟材

並列摘要

The variations of growth ring characteristics and wood fiber length of 30-year-old big-leaf mahogany (Swietenia macrophylla) plantation trees grown in Taiwan were investigated in this study. The experimental results showed that significant differences in average ring density (RD) occurred among three radial stages of ring number (1-8, 9-21, and 22-26 ring number from the pith) and along cross-section height. The RD in the radial direction decreased from the pith outward to the bark, whereas RD increased slowly from the tree base to the tip. There was a close relationship between earlywood width and ring width (RW). Earlywood density, latewood density, and latewood percentage were the major factors governing the overall RD. There was a weak relationship between RW and RD, indicating that it is unlikely for the growth rates of big-leaf mahogany plantation trees to have a significant impact on wood density. The wood fiber length increased significantly from pith to bark and decreased significantly along cross-section height. The boundary determined between juvenile and mature woods in the stem of big-leaf mahogany was 20^(th) growth ring from the pith according to the elongation rate of wood fiber length decreased to 1%.

並列關鍵字

Big-leaf mahogany plantation wood ； Growth ring characteristics ； Wood fiber length ； Juvenile wood