Wood Properties Of Eucalyptus Pellita And Variation Regularities

The anatomical properties, chemical properties, physical and mechanical properties of E.pellita from five families(P4 P5 P9 P17 and P18) in Guangxi-Dongmen Forest Farm have been determined systematically through experiments. Furthermore the obtained data of one point three meters E.pellita families about anatomical index(including fiber length, fiber width, ratio of length to width, double radial wall thickness, ratio of double wall thickness to lumen diameter, ratio of lumen to cell diameter and microfibrilla angle),chemical properties(including the contents of cellulose, pentosan, lignin, 1%NaOH extractive, hot-water extractive, cold-water extractive, ash and PH value of wood) of E.pellita families on the height of one point three meters and physical and mechanical properties(including basic density, shrinkage properties, modulus of elasticity, bending strength, compression strength parallel to grain and compression strength perpendicular to the grain) with height in the tree were analyzed and discussed in details by means of mathematical statistics in order to seek the variance regularity and correlation of wood quality characters. The results indicated that: (l)The index of anatomical and the physical and mechanical of E.pellita families had extremely significant differences at 0.01 level except the variance shrinkage index. Among the six families of E.pellita, lignin contents had obvious difference at 0.01 level, 1%NaOH extractive and the contents of cellulose reached 0.05 and 0.1 level respectively. Whereas there were slight differences in the contents of pentosan, hot-water extractive, cold-water extractive, ash and PH value of wood at 0.1 level.(2)The fiber length increased gradually from pith outward, then decreased gradually at certain age showing a Panshin III variation pattern. Meanwhile the fiber width had the similar regulation to the fiber length. The ratio of length to width decreased gradually from pith outward, reached maximum at certain age, then decreased slightly or level off. From pith outward the double radial wall thickness and the ratio of double wall thickness to lumen diameter increased gradually, while the ratio of lumento cell diameter and the microfibrilla angle decreased gradually. (3) From the base upward, the tangential shrinkage of oven dried wood had no unitary regulation, whereas basic density, radial shrinkage of oven dried wood and volumetric shrinkage of oven dried wood increased gradually, then decreased gradually at certain height. Variance shrinkage decreased gradually.(4)The modulus of elasticity, bending strength, compressive strength parallel to grain and partial tangential proportional-limit of compressive strength perpendicular to the grain increased gradually from base upward, reached maximum at certain height, then decreased gradually. There existed a decreasing trend in partial and total radial proportional-limit of compressive strength perpendicular to the grain from base upward, while total tangential proportional-limit of compressive strength perpendicular to the grain had no unitary regulation.(5)From pith outward cellulose contents increased gradually, whereas the radial variance of pentosan contents had no unitary regulation. Between the families of E.pellita, there were slight differences in the contents of lignin among heart, center and edge. There existed a decreasing trend in 1%NaOH extractive form heart to edge. The center contents of hot-water extractives and cold-water extractives were all bigger than heart and edge. And the contents of ash and PH value of wood increased gradually from heart to edge. (6)Taking microfibrilla angle as independent, fiber length and width as dependent respectively made linear regression analysis. Among E.pellita families a notable negative linear regression was found between microfibrilla angle and fiber shape traits. (7) The linear regression were analyzed by taking basic density as independent, bending strength, compressive strength parallel to grain and volumetric shrinkage of oven dried wood as independent respectively. Between E.pellita families bending strength were positively correlated with basic density, the regression coefficient was above 0.619 and the effect of regression was notable except P18 family whose regression coefficient only reached 0.366.There also exited positively correlation between compressive strength parallel to grain and basic density and the regression coefficient reached above 0.8, while P5 family had weak correlation and the regression coefficient was only 0.245.