Genetic Variation And Correlation In Wood Properties Of Betula Platyphylla In Natural Stands

Five popuplations of Batula platyphylla which grew in natural stands of the northeast part of China was taken as the materials, of which the wood properties including wood anatomic features (fiber form, ratio of fiber wall, tissue proportion and mirofibrillar angle) basic density (BD), small tensile strength and ring width, using variance, regression and correlation analysis, were measured in order to make comprehensive study on variability of the wood properties among and within populations.The results indicated that the fiber length and fiber width of the wood increased gradually from the pith to the bark at first, and then increased slowly when to reach the highest level. With the increasing of age, the fiber cell wall-lumen decreased firstly, and then tended to stable when the trees turned into the fast growth period, and increased again at last. There were no significant differences of fiber length and the fiber cell wall- lumen, and great differences of fiber width and ratio of fiber length to width among populations, but big differences of above characteristics within a population. The distribution frequency of fiber length and width was basically in normal; The regression between fiber length and annual ring indicated that the models of Y=b₀+b₀*x+b₂*x², Y=b₀+b₁*lnx, Y=b₀x^b1 were appropriate to be used as the predicative models for fiber length of the wood.The radial change pattern of wood basic density was the same as fiber length in the populations of Wangqing, Maoershan, Jinshantun and Tahe, but the change in "V" form for Xinbin population, with great variations among populations.The radial pattern of the cell wall ratio fluctuated in a level from the pith to the bark, also with clear difference among the populations for this characteristic. The radial change of the mirofibrillar angle, with big variation among populations, had an opposite trends with fiber length.The radial alteration of fiber proportion and vessel-elements proportion were similar to that of the cell wall ratio, and xylem ray proportion among populations with varying pattern. Variance analysis showed that the fiber and xylem ray proportion among populations were insignificant, but the vessel-elements proportion varied greatly.The radial change of the small tensile strength of the wood was also like that of fiber length, without distinct differences among populations. The radial pattern of annual ring width of the wood was even in Tahe population, and up-down-up-down for other populations, with highly differentiation.Correlation analysis resulted that significant negative correlation existed between the vessel-elements proportion and annual average temperature as well as rainfall, and between cell wall ratio, wood basic density and longitude (r>0.9). In wood properties among populations, distinct positive relationships occurred between wood basic density and cell wall ratio (r>0.9), and significant negative correlation between fiber width and cell wall ratio, thefiber cell wall-lumen, ratio of fiber length to width (r>0. 8) , also between fiber length and mirofibrillar angle (r=-0. 97) .At the same time, we also found some negative correlation between vessel-elements proportion and ray proportion, between basic density and annual ring width within a tree in significant variations (r>0. 6) , and the positive correlation between fiber wall- lumen and cell wall ratio, between fiber length and fiber width, between fiber length and ratio of fiber length to width. Great negative relations between mirofibrillar angle and fiber characters, also between mirofibrillar angle and wood basic density were observed within a tree, except Xinbin population.