broj: 11-12/1997
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| PRETHODNO PRIOPĆENJE | ||
| Prpić, B., Seletković, Z., Tikvić, I. | UDK 630* 919 + 171.3 (001) | |
| On the Influence of the Sava - Danube Canal on Forest Ecosystems pdf HR EN | 579 | |
| IZVORNI ZNANSTVENI ČLANCI | ||
| Trinajstić, I., Franjić, J., Samardžić, I. | UDK 630* 181.1 + 188 : 630* 173.5 + 174.7 (Abies alba Mill.) 001. | |
| About the Importance of the Discovery of the Species Equisetum sylvaticum L. (Equisetaceae) for Understanding the Autochthonism of the Silver Fir (Abies alba Mill, Pinaceae) in Požeško gorje pdf HR EN | 593 | |
| Franjić, J., Škvorc, Ž. | UDK 630* 422 (Quercus Cerris L) 001. | |
| Frost-crack in Some Oak Species (Quercus L., Fagaceae) on Krndija and Dilj (Slavonia, Croatia) pdf HR EN | 599 | |
| Summary: Frost-crack is aphenomenon occurring on woody species in ali areas of the Northern Hemisphere with a distinct hibernalperiod. Its intensity, namely its significance with respect to the forestry and economy as well as the ecology varies depending upon climatic conditions, tree species, etc. Damages caused by the frost-crack are considerable because it does not only damage the lower, economically the most valuable part ofthe tree trunk, but also increases the possibility for a large number ofpathogenic organisms to penetrate into trees. The frost-crack is a very complex phenomenon and most likelv there is not onefactor which can be generalized as its only and main cause, but like ali other phenomena in the ecosystem it results from the interaction of many complicated and often hardly understandable processes in them. The most acceptable theoryfor crack formation in the tree trunk lower parts is the one by which formation of cracks is connected with abrupt and high drops in air temperature, that causesfast cooling and shrinking oftree trunk outer lavers while the inner ones cool very slowly and, therefore, keep their dimensions for a longer time period. As the result, in the outer parts ofa tree trunk there appear tangentialforces which act in two different directions causing cracking. The frost-crack, therefore, occurs as the consequence ofbad thermal conductivity ofwood. The researches ofthe frost-crack on the turkey oak, sessile oak and common oak trees have been carried out in four populations (Kutjevo, Caglin, Rozmajerovac, Levanjska Varoš) on seven trialplots. The average share of frost-cracked sessile oak trees in pure stands is 3.67 % (2 -7%), whilein the mixedstands with the turkey oak this share is 14.67 % (10-20 %), thatis approximately 4 times more (tab. 2). The average share of frost-cracked turkey oak trees in the mixed sessile oak and turkey oak stands is 53 % (43 -64%). This frequency is in the average about 3.5 times higher for the turkey oak thanfor the sessile oak in the same stands. The frost-crack ofthe common oak in the Rozmajerovac population (the common oak with the turkey oak) is 8 %, and that ofthe turkey oak 50 %, showing that the sessile oak is much more susceptible to damage by frost-crack than the common oak (tab. 2). The share of the frost-cracked turkey oak trees changes with a change of exposition, thus it is the biggest (64%) on the North-East exposition (N-E) and the smallest (43%) on the South-East one (S-E), (tab. 3). From the figure 1 it can be seen that according to thicknesses grades the share of frost-cracked turkey oak trees increases with the thickness grade increase in three out of four researchedpopulations (Čaglin, Rozmajerovac, Levanjska Varoš) while only in the Kutjevo population it decreases. Using the statistical and graphical analysis, a general (preliminary) pattern ofthe share offrost-cracked turkey oak trees in the mixed sessile oak and turkey oak stands has been obtained, with a slower the frost-crack share growth due to the inclusion of the Kutjevo population in which because ofthe recently performed thinning this share is decreased (comp. fig. 5). Thus, with regard to the straight Une inclination, the Kutjevo population differs significantly from other researched populations, among which no significant differences exist (tab. 4). The share of the frost-cracked turkey oak trees grows faster, with respect to the thickness growth, in the mixed common oak and turkey oak štand than in the mixed sessile oak and turkey oak stands (fig. 5), mostprobably due to the habitat characteristics (more moisture, morefrequentfrosts). The researches have shown that there are thick turkev oak trees which are not frost- cracked and which have a tree-trunk ofgood quality. The question is very likely about the genotypes resistant to frost-crack which should be preserved by means of silvicultural operations until the end ofrotation while the damaged and non-resistant trees should be eliminated before regeneration. This can be considered only if because of the štand structure or for any other reasons, the turkey oak cannot be eliminated from the sessile oak stands, since not only itperishes by the frost-crack but it also transfers this inferior property ofits to the sessile oak and the common oak with which it grows together in the researched area. | ||
| PREGLEDNI ČLANCI | ||
| Pičman, D., Pentek, T., Mikić, B. | UDK 630* 686 + 383 (001) | |
| The use of Personal Computers in Planning and Drawing up Plans for Forest Roads pdf HR EN | 609 | |
| Turkulin, H., Jirouš-Rajković, V., Grbac, I. | UDK 634.0 814.1 + 634.0 842 (001) | |
| Surface Durability of the Wood Building Constructions pdf HR EN | 617 | |
| Piškorić, O. | UDK 630* 902 (001) | |
| ´Works´ - a Magazine of the Croatian-Slavonian Management Society 1847 - 1852 pdf HR EN | 631 | |
| STRUČNI ČLANCI | ||
| Rauš, Đ., Španjol, Ž., Španjol, B. | UDK 630* 188 + 249 : 630* 156 (Quercus ilex L.) | |
| Scientific and research work in the educational-experimental forest facility of Rab pdf HR EN | 645 | |
| Dimitrov, T. | UDK 630* 432.0 | |
| History of the Canadian Forest Fire Danger Evaluation System Development and the Possibility of its Application in Other Countries pdf HR EN | 657 | |