| This study took five 5-year-old Eucalyptus globulus juvenile wood harvested from Sichuan province as objects, investigated and analyzed fiber and vessel morphologies through isolation and permanent section. The physical-mechanical properties were also tested based on national standards. The result shows that:(1) The vessel length, width (radial diameter), length-width ratio, tangential diameter were 410.13 μm,141.24 μm,2.90,89.25 μm, respectively. The vessel length, vessel width and vessel tangential diameter showed a similar variation in the radial direction that were both decreasing from pith to bark and that the largest increase emerged at the third ring. The longitudinal variation of vessel length and vessel width were increased from the base to 6 m height and decreased then. The longitudinal variation of length-width ratio was contrary with vessel length that decreased from the base to 6 m height and increased as the tree height increased. The longitudinal variations of internal radial direction of 5 growth rings vessel length showed a similar that increased from the base to 2 m height and decreased as the tree height increased (abnormal appeared only at 6 m height).The longitudinal variations of internal radial direction of 5 growth rings vessel width also showed a similar that increased from the base to 6 m height and decreased then. The variation of longitudinal variation of internal radial direction of vessel length-width ratio was not obvious.Analysis by variance showed:vessel length, vessel width, tangential diameter were all significant difference between growth ring. Analysis by correlation showed:the vessel length and vessel width had significant correlation with growth ring, respectively. The vessel length had significant correlation with tree height while the vessel width and length-width ratio had negative correlation with tree height but not significantly. Adopting function curve to fit vessel length (y) and height (x), we got y=-0.4575x2+4.7031x+403.47, R2= 0.8886。(2) The fiber length, width, length-width ratio, cell wall thickness, cavity diameter, cell wall thickness-lumen diameter were 910.27 μm,17.79 μm,50.85,3.47 μm,10.48 μm,0.67, respectively.All the fiber morphology property index but cell wall thickness and cell wall thickness-cavity diameter showed a similar increasing trend, and their radial variations were both decreasing from pith to bark. Longitudinal variation of fiber morphologies were complex that the fiber length showed significant variation namely increased first and then decreased with(3) the increase of tree height while others showed not so regularly.The longitudinal variations of internal radial direction of 5 growth rings fiber length showed a similar that increased from the base to 2 m height and decreased as the tree height increased (abnormal appeared only at 6 m height).The longitudinal variations of internal radial direction of the first growth ring fiber width increased from the base to 6 m height and decreased then. The longitudinal variations of internal radial direction of fiber length-width ratio, cell wall thickness, cavity diameter, cell wall thickness-lumen diameter of different growth rings were inconsistent.Analysis by variance showed:fiber length, fiber cell wall thickness-cavity diameter ratio were all very significant difference between growth ring (P<0.01). The fiber width, fiber length-width ratio, cell wall thickness, cavity diameter were all significant difference between growth ring (P<0.05). The fiber length, fiber width, fiber length-width ratio, cell wall thickness, cavity diameter, fiber cell wall thickness-cavity diameter ratio were all very significant difference between tree height (P<0.01). Analysis by correlation showed:fiber length and fiber length-width ratio had very significant correlation with growth height, fiber cell wall thickness-cavity diameter ratio had significant correlation with growth height while fiber width, cell wall thickness, cavity diameter had not significant correlation with growth height. Adopting function curve to fit fiber length (y1) and fiber length-width ratio (y2) with height (x), we got yj =-0.5051x2-4.3707x+930.66, R2-0.8566; y2=-0.0116x2-0.3217x+52.68, R2-0.5789.(4) The air-dried shrinkages of radial, tangential and volume were 2.38%,4.01%,6.75% and the over-dried shrinkages were 3.71%,5.75%,9.14%, respectively. The air-dried density, dried density and basic density were 0.41,0.46,0.38 g/cm3.All three densities showed a similar variation from pith to bark namely decreased first and increased then. In the axial direction, they were unchanged from the base to 2 m and dropped to the smallest at 4 m height and increased within the increasing of stem height above 4 m. The longitudinal variations of internal radial direction of all three densities showed a similar that the variation from base to 2 m height were not obvious and that decreased with the increase of tree height until 4 m or 6 m height and increased then. The air-dried density had a very significant correlation with basic density and we got that y=1.2531x-0.0118, R2=0.9464. While that the dried density had a significant correlation with basic density and we got y=1.2833x-0.068, R2=0.9671.(5) The compressive strength parallel to grain is 24.80MPa, the bending strength is 58.26MPa, the bending elastic modulus is6444.24MPa, the shear strength parallel to grain is(6)2.31MPa and the hardness in end, radial and tangential section are 3.10kN,2.20kN, 1.96kN, respectively. The composite strength is 83.06MPa belongs to low level. Analysis by correlation showed:All the mechanical property index had significant or very significant correlation with basic density include negative correlation between shear strength parallel to grain and basic density, mechanical property indexes except shear strength parallel to grain had significant or very significant correlation between any two. shear strength parallel to grain had not significant correlation with bending elastic modulus, bending strength, compressive strength parallel to grain,hardness in end and radial section. |
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