紅檜生材含水率與密度在單株間與單株內之變異

Inter-tree and Intra-tree Variations in Moisture Content and Wood Density in Red Cypress (Chamaecyparis formosensis Matsum.)

邱志明(Chih-Ming Chiu) ； 林振榮(Cheng-Jung Lin) ； 唐盛林(Sheng-Lin Tang) ； 蔣華蕾(Hua-Lei Chiang)

《台灣林業科學》 21卷2期 (2006/06) Pp. 233-248

https://doi.org/10.7075/TJFS.200606.0233

摘要

各性質間，容積密度和生材含水率為負相關，而生材比重和生材含水率呈正相關之趨勢，其關係均為二次曲線之關係；生材比重和容積密度則呈直線正相關。又林木生機愈旺盛，冠幅愈大，胸徑亦愈大，而林木胸徑和立木生材含水率及生材比重呈正相關，但和立木之容積密度之關係則不明顯。
本研究調查46年生紅檜人工林75株，其立木生材含水率、生材比重及容積密度在單株間及單株內樹幹不同位置之變異，並探討生長特性和其性質間之關係，以提供立木非破壞檢測、動彈性推估及生物量、碳吸存估算之參據。結果顯示胸高部位不同單株間生材含水率由102.9~208.5%，平均147.8%，變異係數19.4%，單株內徑向變動之趨勢最低點在心邊材轉移帶之位置，至於邊材和心材含水率之高低，視個體而異，但樹高方向，枝下高以上，邊材含水率大於心材含水率。容積密度不同單株間胸高部位之變異由0.337~0.432 g cm^(-3)，平均0.392 g cm^(-3)，變異係數10.0%，徑向部位，邊材比心材有較高之密度，樹高部位，樹冠部比樹幹基部有較高之容積密度。生材比重在個體間之變化由0.772~1.137，平均0.963，變異係數11.5%，單株內之變化，徑向以心邊材轉移帶最小、樹高方向則變異不明顯。又由變異組成分分析知，紅檜人工林不論立木生材含水率、容積密度及立木生材比重均發現單株內不同位置之變異大於單株間之差異。

關鍵字

紅檜 ； 含水率 ； 容積密度 ； 生材比重

並列摘要

There was a significant negative relationship between the basic density and green moisture content, but a positive relationship between green specific gravity and basic density. The values of green specific gravity increased with an increase in the moisture content. Their relationships could be represented by a 2nd-order polynomial regression model. Trees with stronger characteristics not only had wider crown widths, but also larger diameters at breast height (DBH). The DBH values tended to increase with increasing moisture content and green specific gravity, but there was no significant relationship between DBH and basic density.
Inter-tree and intra-tree variations in green moisture content, green specific gravity, and basic density in stems of red cypress (Chamaecyparis formosensis Matsum.) were investigated in seventy-five 46-yr-old plantation trees. In addition, the relationships of growth characteristics and wood properties were explored. The results provide basic information for nondestructive evaluation and calculations of the dynamic modulus of elasticity, biomass, and carbon storage of standing trees. The average green moisture content value among the sampled trees at breast height position was around 147%, and ranged from 102.9 to 208.5%, with a difference of 19.4%. Five radial positions were defined: a core piece (including the pith), inner heartwood, outer heartwood, transition wood, and sapwood. Results showed that average values of the green moisture content obtained from transition wood were significantly lower than those for the other positions. According to a statistical analysis, no significant differences (p＞0.05) existed for the green moisture content between sapwood and heartwood, but significant differences (p＜0.05) existed between sapwood and heartwood in the live crown. The inter-tree variation in average basic density was around 0.392 g cm^(-3), and ranged from 0.337 to 0.432 g cm^(-3), with a difference of 10%. Basic density in sapwood was higher than in heartwood, and that in stems of live crowns was higher than that in basal stems. The average green specific gravity was around 0.963, and ranged from 0.772 to 1.137, with a difference of 11.5%. Average values of the green specific gravity obtained from transition wood were significantly lower than those for the other positions; however, no significant differences existed in different tree height positions. According to a variance component analysis, within-tree variations in green moisture content, green specific gravity, and bulk density were greater than tree-to-tree variations.

並列關鍵字

red cypress Chamaecyparis formosensis Matsum. ； moisture content ； basic density ； specific gravity in green wood