| This paper research on the bark, fiber molecules, organization content, physical and mechanical properties of wood of E.urophyllaxE.grandis which is 5-year-old,6-year-old,7-year-old and growing in Ping tian shan Forestry of Gui gang for objects.The resultus are as follow.(1)The weight bark rate of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 13.76%,10.92%,10.1%; Each Volume bark rate of them are 11.69%,10.52%,8.97%.Volume bark rate and weight bark rate of different age of trees are gradually decreasing with the height of trunk increase.(2) The length,width, wall thickness, ratio of length to width, ratio of wall thickness to cavity diameter of phloem fiber of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 1168.22μm,1139.65μm,1287.28μm; 18.09μm,18.86μm,17.89μm; 10.45μm,10.99μm,10.10μm; 64.58,60.44,72.47; 1.37,1.41,1.30. The width, wall thickness, ratio of wall thickness to cavity diameter of phloem fiber are gradually reduced with the height of trunk increase. The length, ratio of length to width variation of phloem fiber are not obvious with the height of trunk increase.Analysis by variance shows:the length of phloem fiber and the ratio of length to width is significant difference between different age of trees. The ratio of wall thickness to cavity diameter of phloem fiber is not significant difference between different age of trees.(3) Conduit molecules percentage, fiber percentage, wood ray percentage of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 2.75%,14.28%,13.19%; 69.31%,68.55%,70.09%; 18.12%,17.18%,16.88%. The variation of conduit molecules and fiber percentage is not obvious with the height of trunk increase.However the wood ray percentage gradually reduced with the the height of trunk increase.Analysis by variance shows:conduit molecules percentage, fiber percentage is not significant difference between different age and height of trees, but wood ray percentage is not significant difference between different height of trees. On the upward, conduit molecules percentage is significant difference. Fiber percentage and wood ray percentage is significant difference between different age of trees.(4) The fiber length,width, wall thickness, ratio of length to width,ratio of wall thickness to cavity diameter of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 953.63μm,976.01m,1006.40μm; 19.58μm,20.14μm,20.22μm; 6.90μm,7.38μm,7.03μm; 48.58,48.28,49.65; 0.55,0.58,0.53. The variation of fiber length,width, wall thickness, ratio of length to width,ratio of wall thickness to cavity diameter is not obvious in the longitudinal, however gradually increases from center of pith to outside.Analysis by variance shows:in the longitudinal, fiber length is very significant difference between different age and height of trees, Fiber width and ratio of length to width is significant difference between different age of trees, Ratio of length to width is very significant difference between different height of trees, Ratio of thickness of wall to cavity diameter is not significant different. On the radial, fiber length and ratio of length to width is significant difference between age, and is very significant difference between ring.Fiber width is very significant difference between growth ring.Ratio of thickness of wall to cavity diameter is significant difference.(5) S2 microfibril angle of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis is 11.87°,12.17°,13.23°. The variation of S2 microfibril angle is not obvious with the the height of trunk increase, and is gradually reduced in the radial.Analysis by variance shows:S2 microfibril angle is not significant difference in the longitudinal. S2 microfibril angle is significant difference between growth ring.(6) The density of green wood,basic density, air dry density of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 1.027 g/cm3,1.037 g/cm3,1.031 g/cm3; 0.436g/cm3,0.475 g/cm3,0.461 g/cm3; 0.53 g/cm3,0.58 g/cm3,0.583 g/cm3. The variation of green wood density,basic density,air dry density is not obvious in the longitudinal,and gradually increased in the radial.Analysis by variance shows:green wood density is significant difference in the radial. Basic density is very significant difference in the longitudinal,and basic density is significant difference between age in the radial.(7) The compressive strength paralle to grain of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 46.8Mpa,50.1 Mpa,51.4 Mpa. Compressive strength paralle to grain gradually increased with the height of trunk increase.Analysis by variance shows:compressive strength paralle to grain is not significant difference between age and height.(8) The bending strength, bend elastic modulus 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 89.6 Mpa,101.6 Mpa,102.76Mpa; 8762Mpa,9935Mpa,9869MPa. The variation of bending strength and bend elastic modulus is not obvious in the longitudinal.Analysis of variance shows:bending strength and bend elastic moduluse is not significant differenc between between age and height.(9) The shearing strength parallel to grain 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 9.6Mpa,9.7 Mpa,9.5 Mpa. Shearing strength parallel to grainl is reduced first and then increased on the radial,and is increased first and then reduced on the tangential with increase of height and age. Analysis of variance shows:radial shearing strength parallel to grain is not significant differenc between age and height. Shearing strength parallel to grain on the tangential is significant difference between age.(10) The partial and total compressive strength perpendicular to the grain of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 11.3Mpa,10.7 Mpa,10.5Mpa; 9.4Mpa,10.0Mpa,9.5Mpa. Partial compressive strength perpendicular to the grain increased first and then reduced. With the increase of height, radial partial compressive strength perpendicular to the grain gradually reduced and tangential partial compressive strength perpendicular to the grain increased firstly and reduced then. Radial and tangential total compressive strength perpendicular to the grain gradually increased with increase of height, and reduced with the increase of age.Analysis of variance shows:partial compressive strength perpendicular to the grain is not significant difference. Total radiall compressive strength perpendicular to the grain is not significant difference in the longitudinal, and is significant difference between age.Tangential total compressive strength perpendicular to the grain is significant difference in the longitudinal, and is very significant difference between age.(11) Hardness of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 3.81 KN,3.90 KN,3.66 KN. Hardness of wood increased first and then reduced with increase of height and age.Analysis of variance shows:hardness of the port side of wood is significant difference.The radial hardness of wood is very significant difference in the longitudinal,and is not significant difference between age. The tangential hardness of wood is very significant difference.(12) The cleavage resistance of 5-year-old,6-year-old,7-year-old E.urophylla×E.grandis are 235N/mm,238N/mm,240 N/mm. In the longitudinal, cleavage resistance of wood reduced first and then increased. With increase of age, cleavage resistance of path surface increased first and then reduced, tangential cleavage resistance of wood reduced first and then increased.Analysis of variance shows:radial cleavage resistance of wood is significant difference in the longitudinal, and is not significant difference between age. Tangential cleavage resistance of wood is not significant difference in the longitudinal and between height. |
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