Wood anatomy of Chinese fir in different site types of its southern growing district.

In order to investigate the differences of wood anatomy of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook) among different site types and to provide more theoretical instructions for cultivating fast-growing wood and improving wood properties, this paper discusses wood anatomic characteristics of Chinese fir obtained from southern slopes, mountain valleys, mountain ridges and mountain tops from 2001 to 2003. The samples come from 12~13-year-old trees in Gaofeng Forestry Center in Guangxi Zhuang Autonomous Region. The macroscopic and microscopic methods are employed. The research results show that: 1) There are significant differences in both growth ring width and latewood percentage among different site types. The growth ring widths of four site types increase at first and then decrease with an increase of age in a radial direction.The same trend is observed with increasing height in a longitudinal direction. However, there is no obvious trend in the changes of latewood percentage in both radial and longitudinal directions. 2) The differences in thickness of the cell wall and the ratio of cell wall to cavity are significant, while the differences in tracheid length, width and ratio of length to width are insignificant. Their radial variations are similar, but longitudinal variations vary with site types. 3) The differences of microfibrillar angle among different site types are not noticeable. It gradually decreases with the increase of ages in radial variation. But in a longitudinal direction, it appears as “big-small-big" with an increase in height. 4) The differences in proportion of wood tissues are insignificant. 5) There are marked differences in air-dried density.