Variation Patterns Of Tracheid Anatomical Characteristics And Basic Density For Chamaecyparis Pisifera

In this paper the variation patterns of latewood percentage, wood anatomical characteristics (Tracheid morphological features, microfibrillar angle ) and basic density in radical and axial directions are mainly analysised for C. pisifera, the correlation among them and the juvenile period were investigated, the results were as follows:From pith outward, the annual ring width decreases rapidly in 1～9a, and then levels off. In the axial direction, the variation of annual ring width is ruleless; The variation model of latewood percentage in radial direction is different with the annual ring width, increases all the time. And 10～13a is a important transition. The variation of latewood percentage is ruleless in axial direction.The mean values of earlywood of tracheid length, diameter, double wall thickness, length-width ratio, double wall thickness-diameter ratio and diameter-width ratio is 1.93mm, 33.3μm, 4.15μm, 51.39, 0.131 and 0.884 respectively. The mean values of latewood is 2.07mm, 23.0μm, 5.67μm, 73.55, 0.256 and 0.798.The tracheid lenth increases rapidly before 11a in radial direction, and then increases slowly. It varies little in the 11～26a, but has some fluctuations after 26a. The variations of tracheid diameter and tracheid double wall thickness are similar to each other in radial direction, from pith outward increase firstly and then level off, but the extent of tracheid double wall thickness'variations is not big; The variations of tracheid length-width radio is similar to the tracheid lenth, tends to level off after 11a as well; The variations of double wall thickness-diameter ratio is different with the tracheid lenth. From pith outward, double wall thickness-diameter ratio decreases, and levels off after 10a. In total, it tends to downtrend, and the extent of variation is biggish near the bark.Along stem height, the tracheid lenth increases progressively from the base upward, maximizes at 3.3m～5.3m, and decreases to the top of the tree. The axial direction variation tends to "short-long-short" pattern, belongs to the familiar model of axial direction variation; The tracheid diameter increases from the base upward, maximizes at 1.3m～3.3m, and decreases to the top of the tree; The double wall thickness from the base upward, along the stem tends to decrease; The tracheid length-width ratio's axial direction variation is is similar to the tracheid lenth; The tracheid double wall thickness-diameter ratio from the base upward decreases firstly, and then levels off, and increases to the top of the tree. The microfibrillar angle variation of earlywood in radial direction is similar to the latewood. They also decrease rapidly in 1～13a, and decrease slowly after 13a. In radial variation the microfibrillar angle of earlywood and latewood are according to "rapidlly decrease - slowly decrease - level ofF" pattern. The mean value of microfibrillar angle of C. pisifera is 20.29°, the earlywood is 20.98°and the latewood is 19.59°. The value of earlywood is significantly larger than that of latewood in the same annual ring, about 1.39°. Microfibrillar angle decreases along stem height until it comes to the least, and then increases slowly to the top.The mean value of basic density of C. pisifera is 0.334g/cm~3. From pith outward, basic density decreases rapidly before 11a, and then decreases slowly. Panshin and Zeeuw researched the variation patterns of wood basic density, and thought that there were three major patterns of variation occur. And C. pisifera belongs to the third pattern. The variation of basic density in axial direction increases upward and then decreases, and increases again to the top. In a word, the basic density of base is maximal, and the top of tree is minimum.The coefficient of variability of tracheid length within trees is larger than that of among trees. The coefficient of variability of tracheid double wall thickness-diameter ratio among trees is 0.5%～10.4%, and less than that within trees in evidence. The coefficient of variability of tracheid diameter, double wall thickness, length-width ratio, diameter-width ratio, basic density and the content of extractives within trees are also larger than that of among trees, but not markedness as tracheid length and double wall thickness-diameter ratio.From pith outward, basic density tends to decrease. But the latewood percentage increases all the time. Compared the correlation between the basic density and latewood percentage, finds that correlation is negative, and the coefficient is -0.7301. But there is the positive correlation between the basic density and content of extractives, and the coefficient is 0.8452, the positive correlation is significant at 0.01 level. These speaks volumes for that the basic density is significantly affected by the content of extractives, and it's radical variation is also mainly affected by the content of extractives.The coefficient between basic density and tracheid length, diameter, double wall thickness, length-width ratio, double wall thickness-diameter ratio and diameter-width ratio is -0.9237, -0.9530, -0.9054, -0.8266, 0.6504 and -0.7783. All of them are significant at 0.01 level. These indicates that the basic density is significant negative correlation with tracheid length, diameter, double wall thickness, length-width ratio and diameter-width ratio. And it is just significant positive correlation with double wall thickness-diameter ratio.There is significant negative correlation between the microfibrillar angle and tracheid length, diameter, double wall thickness, length-width ratio and diameter-width ratio. The relative coefficient is -0.9214, -0.9022, -0.8212, -0.8746 and -0.7995. The microfibrillar angle is just significant positive correlation with double wall thickness-diameter ratio, and the coefficient is 0.6920. The correlation between tracheid morphological features and microfibrillar angle can forecast the variation of microfibrillar angle.The juvenile period of C. pisifera can be confirmed about 11a under the consideration of the variation of latewood percentage, tracheid morphological features, basic density and microfibbrillar angle in radial direction. There are many differences in anatomical characteristics and some other things between juvenile wood and mature wood by compared, and the differences are very significant.