Comparative Study On The Growth Stresses And The Properties Of Normal Wood And Compression Wood In Masson Pine

In the study, 3 straight and 3 curve trees of Masson Pine(Pinus massoniana Lamb.) were got in Daliu forest station of Sha heji county, Chuzhou city, Anhui province. The growth stresses, wood properties and radial variation among normal wood, compression wood, opposite wood and side wood were studied. The wood properties include the anatomical feature, the microfibril angle, the growth ring width, the latewood percentage, the density, ten shrinkage and the mechanical properties. The axial variation of anatomical features and basic density were studied in normal wood. There are no significant differences in growth stresses among different normal woods and directions on the same height of stem. The stresses were higer in compression wood than in normal wood, opposite wood and side wood. The stresses were lower in normal wood than in opposite wood and larger in normal wood than in side wood. All differences were significant. There are positive correlations between h/d-value, lean angle, asymmetric crown and growth stresses and there is a negative correlation between crown projection and growth stresses. These trees tend to have high stress levels, which show slender long stems(high h/d-value) and narrow crowns or lean stems and asymmetric.Shorter tracheid lengths, smaller tracheid diameters, smaller lumen diameters, thicker tracheid radial walls, flater microfibril angles, width growth rings, higher latewood percentage and higher wood density are the characteristics of compression wood compared with those of normal wood. The analysis of variance shows that there are significant differences between compression wood and normal wood in mostly tracheid features, but there are no significant differences in latewood tracheid tangential diameter, latewood lumen radial diameter, tracheid tangential wall thickness, ratio of wall thickness to lumen and lumen to diameter. The axial-shrinkage was about 4 times higher in the compression wood than in the normal wood. The radial-shrinkage, tangential-shrinkage and volume-shrinkage of compression wood are smaller than that of normal wood respectively when the wood has been absolute-dried and air-dried. Analysis at 0.001 level variance showed that the different of axial shrinkage between compression wood and normal wood is obvious. There are also significant differences between compression and normal wood in shrinkage excepting of air-dry radial shrinkage. The MOR and MOE of normal wood were higher than those of compression wood, while the crushing strength was reverse. All the differences reached 0.01 level of significance. Regressive analysis shows that the normal-wood MOR, MOE, and crushing strength positively correlated to wood density with high significance, while no significant correlation was shown between the MOR, MOE, and wood density in compression wood.The average of some properties of the compression wood such as tracheid lengths, tracheid diameters, lumen diameters are smaller than that in the opposite wood and side wood. The tracheid length of side wood which is the longest among three wood is shorter than that of normal wood. Thickest tracheid radial wall, highest ratio of wall thickness to lumen, flattest microfibril angle, widest growth ring, highest latewood percentage and basic density are characteristics of the compression wood compared with those of the opposite wood and side wood. Mostly variances among compression wood, opposite wood and side wood are significant, while some variances such as growth ring width and basic density between opposite wood and side wood are not significant. The air-dry and oven-dry of axial-shrinkage and crushing strength were higher in the compression wood than in the opposite wood with significance over 0.01 level. The air-dry and oven-dry of radial-shrinkage, tangential-shrinkage and volume-shrinkage of compression wood are smaller than that of opposite wood respectively without significant differences.From pith outward, the tracheid length, the tracheid tangential diameter, the tracheid radial diameter, tracheid wall th...