A Study on Moisture Distribution of Green Wood and Variations of Specific Gravity in Crytomeria japonica D. Don

柳杉生材水分分布及比重變異之探討

陳玉秀(Yuh-Shiow Chen) ； 黃彥三(Yan-San Huang) ； 陳欣欣(Shin-Shin Chen)

《台灣林業科學》 13卷2期 (1998/06) Pp. 91-100

https://doi.org/10.7075/TJFS.199806.0091

摘要

本研究乃探討柳杉(Cryptomeria japonica D. Don)造林木之含水率(moisture content)、比重(specific gravity)、體積收縮率(percentage of volumetric shrinkage)及管胞長度(tracheid length)縱向及橫向變異。試樣二株，約43年生，採自台灣省林業試驗所六龜分所、扇平工作站。由結果顯示柳杉生材水分隨樹高之上升而下降，比重則隨樹高之上升而增加。在纖維飽和點下，木材乾燥時體積收縮率與比重成正相關，水分之徑向分布顯示明顯的乾材與濕材帶，心材與邊材間之移行材(intermediate wood)在立木狀態下之水分梯度突降，邊、心材皆以濕材呈現，有別於一般乾燥心材。而管胞長度則由髓心往樹皮處增加，至一最大值後，即不再明顯增加，顯係已達成熟齡。

關鍵字

比重 ； 含水率 ； 飽和度 ； 體積收縮率 ； 解析

並列摘要

This study deals with the distribution of moisture in green wood of standing trees of planted Crytomeria japonica D. Don. The radial and longitudinal variations of specific gravity, volumetric shrinkage, and tracheid length were also investigated. Two trees of about 43 yr of age were sampled from Shanping Station, Liukuei Research Station, Taiwan Forestry Research Institute. The results show that both wet wood and dry wood were present in the stems of the sampled frees. The moisture content of wet wood area is rather high, even reaching its moisture saturation point in heartwood. The dhy zone area occurs in the sapwood adjacent to the boundary of the heartwood. The degree of saturation in the dry zone is only 1t2 to 1/3 that of wet wood. The specific gravity of wood increases from the stump upward to the crown. The percentage of volumetric shrinkage correlates positively with specific gravity, while the moisture content shows a negative correlation with specific gravity. The tracheid lengths increase from the pith outward to a maximum during the maturation of the wood, after which the length remains approximately constant.

並列關鍵字

specific gravity ； moisture content ； volumetric shrinkage ； degree of saturation ； maceration