台灣主要經濟樹材組織構造變異性之研究（I）－針葉樹材之樹幹之直徑、比重、細胞壁率與邊心材率

Abstract

The main purpose of this study is to investigate the variation of trunk diameter, specific gravity, cell wall percentage, and heartwood ratio in the transversal and axial direction on single stem of Taiwan red cypress, Taiwan yellow cypress, Taiwan hemlock, Luanta fir, Taiwan. fir, Taiwan spruce wood species. The experimental results are summerized as follow: (1) The variation of stem diameter at different height of tress have the same trend, the stein diameter decreases from the stump to the top and the regression slopes of diameter variation are in the follow order: Taiwan hemlock＞Taiwan red cypress＞Taiwan yellow cypress＞Luanta fir＞Taiwan fir＞Taiwan spruce. (2) The variation of specific gravity in the transversal direction has six 'types: Type A: Specific gravity decreases from pith to bark (Taiwan red cypress; Taiwan hemlock 2/4H & 3/4H South). Type B: A high specific gravity is near the pith and decreases outward for the first few years, after that it will increase again and decrease to the bark (Taiwan yellow cypress; Luanta fir; Taiwan hemlock 1/4H). Type C: Specific gravity increases outward for the first few years and decreases to the bark (Taiwan hemlock 0/4H). Type D: Specific gravity decreases from pith to sapwood and then increases to the bark (Taiwan hemlock 2/4H, 3/4H North). Type E: Specific gravity decreases outward for the first few years and increases to the bark (Taiwan spruce).Type F: Specific gravity increases from pith to the bark (Taiwan fir). (3) The variation of specific gravity in the axial direction has three forms: Form 1: Specific gravity increases from the stump to the top (Taiwan red cypress; Taiwan hemlock; Taiwan spruce). Form 2: Specific gravity decreases from the base to the middle part of trunk and then increases to the top again (Taiwan yellow cypress; Luanta fir). Form 3: Specific gravity increases from the stump to the middle part of trunk and decreases to the top trunk (Taiwan fir). (4) The variation of cell wall percentage in the transversal and axial direction is the same as the variation of specific gravity. There are six types in the transversal and three in axial direction. (5) The relationship between specific gravity and cell wall percentage highly significant (at 1% level). (6) Heartwood ratio decreases from the stump to the top, and the average heartwood ratio are Taiwan yellow cypress: .83.85%, Taiwan red cypress: 73.88%,Luanta fir: 69.93%, Taiwan hemlock: 55.81% respectively.