DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 3-4/1967 str. 28 <-- 28 --> PDF |
b) physisacl properties: timber´s moisture, breadth of rings, density at 0,;V», 12°/o and nominal, radial, tangential and volumetric shrinkage, fibre saturation point. Fibre lengths in axial direction increase till 3,30 m, and after this heigtht decrease. In the direction of radius hengths increase to 30 years. Average value for all sample-trees and heights is-988 microns. Dimensions of fibres are shown in the table 1 from which it can be concluded that breadth of fibres increase with age, but decrease with height. Averege breadth of fibres is 24,38 microns. The same course has lumen´s diameter, which is the largest in the age of 40 years — 17,51 microns and the smallest in the age of 10 years — 14,49 microns. Double-wall thickness is cca 32;,/o of fibre´s breadth. An analysis of variance in factorial experiments has shown that the significant differences at ll;l/o level were obtained only for sample-trees for fibre length and breadth, and for lumen´s diameter, but not for double-wall thickness. On picture 1 are presented the course of growth-rings at breast height in the direction of east. Mean value of growth-rings without regard to age and height for all sample- trees is 4,7 mm, in which participates early wood — 2,0 mm or 43,2´Vo. Growth rings are broader in juvenile age (1—10 years). Percentage of moisture increse from core to bark. Mean value for whole stem fifteen months after falling was ll,01,0/u. The wettest timber was at height 8.30 m above ground. Specific gravities at breast height are: at Ol´/o moisture: 0,312—0,401—0,480 p/cm3 at 12°/o moisture: 0,344—0,424—0,506 p/cm3 From above data we can determine timber of our willows as low density. Variation of nominal density according to age and cross-section heights are presented in tab. 4, from which we can conclude that basic density increase in horizontal axe, from meat to age of 30 years, and in vertical axe to crown. Data for this property are: 0,290—0,365—0,459 p/cm3 Using »zero-hypothesis« we got by all investigated densities significant differeneces for sample-trees. Radial shrinkage varried from: 1,42 to 5,30Vo with mid-value: 2,91°/o. Tangential shrinkage has given results: 5,28—8,88—ll,28l:7o and volumetric 7,80—12,00— 15,70%), wich are shown in the table 5. Linear shrinkage are not significant in the age 1—10 and 11—20 years. For volumetric shrinkage as well as for sample-trees in linear shrinkage we got significant differences. Fibre saturation point, obtained on samples from breast-height, varries in diapason 24,40—33,92—44,780/o. Porosity decrease with the age, as well as shrinkage. For all physical properties we obtained significant differences for sample trees, on which ground we can conclude that within the investigated population of Salix alba L. there exists genetic variability in respect of tested wood fibre characteristics (with except double-wall thickness) and physical properlies. |