Radial Variation of Anatomical Properties of Betula platyphylla Wood in Different Slope Directions of Northern Hebei Province

The 50 a natural Betula platyphylla woods in the mountain area of northern Hebei Province were measured. The influence of different sloped direction on the fiber morphology and tissue ratios of B.platyphylla was analyzed. The results show that the average values including wood fiber length, the ratio of length to width, fiber double wall thickness-diameter ratio, fiber proportion in shady slope are greater than those on half shady slope, while the average values such as fiber width, vesel-elements proportion, wood ray proportion are less than those on half slope. The radial variation trend of wood fiber length, fiber width and fiber length-width ratio of B.platyphylla on different slope directions is initially increased and then tends to be increased steadily from pith to bark; the fiber double wall thickness-diameter ratio is increasing or decreasing in the radial direction. The vessel-elements proportion, wood ray proportion and fiber proportion are basically fluctuating on a horizontal line from pith to bark. The slope direction has an influence on the wood fiber length, and has a significant influence on the ratio of length to width, but has no significant effect on other anatomical properties such as fiber width, fiber double wall thick-diameter ratio and tissue proportion. The polynomial equation has a good fitting effect on fiber properties and growth ring. As for the B.platyphylla, which will become the mature wood when growing up for over 20 years. According to the anatomic properties, the natural B.platyphylla wood on shady slope and half shady slope are suitable for pulping and papermaking.