broj: 3-4/1960
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| ISKORIŠČAVANJE ŠUMA | ||
| Tomaševski Stanko | ||
| Loss of increment in Beech in consequence of the frozenthrough foliage. PDF EN | 65 | |
| UREĐIVANJE ŠUMA | ||
| Klepac, Dušan | ||
| A contribution to the better knowledge of management of Aleppo Pine forests. PDF FR | 74 | |
| ISKORIŠČAVANJE ŠUMA | ||
| Bićanić Branko | ||
| The stumpage price of the resin and the economic justification of resin-tapping. PDF EN | 85 | |
| Horvat Ivo | ||
| A contribution to the knowledge of some physical and mechanical properties of the wood of White and Black Poplars (Populus alba L. et Populus nigra L.). PDF EN | 95 | |
| Summary: Described are the results of investigation into the some physical and mechanical properties of Silver and Black Poplar-wood. There were investigated 10 sample trees of Silver Poplar-wood (Populus alba L.) and 10 sample trees of Black Poplar-wood (Populus nigra L.) from the forest district Lipovljani. The aim of this investigation was: a) to examine some physical and mechanical properties of Silver and Black Poplar-wood from the forest district Lipovljani, b) to establish the differences between the physical and mechanical properties of Silver and Black Poplar-wood. From the sample trees were prepared 20 sample sections (bolts). These section were taken at breast height of the sample trees. The length of these sections was 1.0 m. From these sample sections were made and examined 1313 specimens of Silver Poplar-wood and 1.081 specimens of Black Poplar-wood. Measured and investigated were the following physical and mechanical properties of Poplar-wood: annual-ring width, specific gravity in air-dry and oven-dry state, nominal specific gravity, radial, tangential and volume shrinkage; static bending strength, impact bending strength, compressive strength, modulus of elasticity, hardness by Janka and Brinell method, and the moisture content of specimens. On the basis of these investigations it is possible to draw the following conclusions: 1. The annual-ring width of Silver Poplar-wood (3.34 mm) is slightly greater than the anual-ring width of Black Poplar-wood (1.69 mm). The difference in the annual-ring width between Silver and Black Poplar-wood is significant. 2. The specific gravity in oven-dry state of Silver Poplar-wood (0.413 g/cm3) is equal to that of Black Poplar-wood (0.412 g/cm3). In the analysis of the relation between the annual-ring width and the specific gravity it was established the following: the specific gravity of the wood possessing the annual-ring width up to 2 mm. is greater in Silver Poplar-wood than in Black Poplar-wood; the specific gravity of the Silver and Black Poplar-wood having the annual-ring above 2,0 mm in width is are well-nigh equal. The greatest specific gravity of Silver and Black Poplar-wood was found in annual-rings displaying a width from 1,5 to 2,0 mm. 3. The radial, tangential and volume shrinkage of Silver Poplar-wood (4.4, 8.5, 13,7%) are some what smaller than the same properties in Black-wood (4.7, 8.8, 14.4%). The differences in radial, tangential and volume shrinkage between the Silver and Black Poplar-wood are not significant. 4. The static bending strength, impact bending strength, compressive strength and modulus of elasticity of Silver Poplar-wood (324 kg/cm2, 0,492 mkg/cm2, 422 kg/cm2 and 87727 kg/cm2) are slightly greater than the same properties in Black Poplar-wood (317 kg/cm2, 0.450 mkg/cm2, 409 kg/cm2 and 82142 kg/cm2). The differences in static bending strength, impact bending strength, compressive strength and modulus of elasticity between the Silver and Black Poplar-wood are not significant. The hardness established by Janka-method in Silver Poplar-wood (280 kg/cm2) is slightly lower than the property in Black Poplar-wood (312 kg/cm2). The difference in hardness (Janka) between the Silver and Black Poplar-wood is significant. Generally, it can be said, that the Silver and Black Poplar-wood is of small density, moderate shrinkage, moderate compression and impact bending strength, have low static bending strength, small elasticity as well as desplaying a mild quality. | ||
| ŠUMARSKO ŠKOLSTVO | ||
| Turk Z. | ||
| Practical qualification examination. PDF EN | 116 | |