DIGITALNA ARHIVA ŠUMARSKOG LISTA
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| ŠUMARSKI LIST 11-12/2003 str. 32 <-- 32 --> PDF |
M. Idžojtić, R. Pernar, 2. Kauzlarić, M. Abramović, D. Janković, M. Pleše: INTENZITET ZARAZE ... Šumarski liši br. II- 12, CXXV1I (2003). 545-559 Prpić, B., Z. Seletković & P. Jurjević 2001: Zuber, R. 1983: Forstschutz. In: Wald- und Forst- Sušenje jele i promjene "kemijske klime". U: Wirtschaft in Graubünden. Ründnerwald, Bei- Prpić, B. (ur.): Obična jela (Abies alba Mill.) u heft 12: 115. Hrvatskoj. Akademija šumarskih znanosti, Hrvatske šume, Zagreb. 299-307 pp. Summary: Mistletoes are epiphytic angiosperms living as semi-parasites on trees and shrubs. Viscum album L. is an evergreen, dioecious species, with opposite forky branching, white, sticky fruits of the Viscaceae family. This species has three subspecies, which can be most easily differentiated according to their hosts. The subspecies Viscum album L. ssp. abietis (Wiesb.) Abrom. appears in Croatia only on silver fir trees (Abies alba Mill), on which it is a parasite in natural forests. The greatest role in the dissemination of mistletoe fruits have birds, especially the mistletoe thrush (Turdus viscivorus L.). So far there has been no systematic research on mistletoes in Croatia, and consequently, no systematic research of mistletoe on fir trees. This paper presents the results of a several-year research of the intensity of mistletoe infestation on silver fir trees in natural stands of silver firs in areas managed by Hrvatske šume (Croatian Forests) Co. Ltd., Forest Administration Delnice. The research of mistletoe infestation was carried out along with the evaluation of fir-tree damage during 5 years, from 1998-2002. Silver fir trees were examined from upper tree layer, whose crowns were clearly visible. For the examined trees it was recorded whether they were infested with mistletoe, whereas the degree of damage, i.e. the percentage of fallen needles and change of their color were evaluated according to the ICP-Forests method. On the area of 12 forest offices 21 management units were examined, 492 forest compartments in which the percentage of fir trees is higher than 50 %, including 68,256 trees in total. The mapping was carried out on the basis of digitalized borders of management units and the research results. In the computer application ArcView 3.3 a layer was introduced in which the spatial distribution of mistletoe infestation on silver fir trees was presented based on management units. The obtained results show that the presence of mistletoe on silver fir trees is considerable. On the whole area of the Forest Administration Delnice almost a third of the examined silver fir trees was infested with mistletoe (32.8 %). The intensity of infestation is relatively small in the degrees of damage of silver fir trees from 0 to 2a (degree of damage 0-40%) and amounts to 1.5% of all examined trees. The highest number of trees, 18 % of all the examined ones, is damaged from 41 - 60 % (degree of damage 2b). Most of the non-infested trees has this degree of damage, 41 %. The intensity of infestation of the 3a degree is 9 %> (degree of damage of silver fir trees 61 - 80 %>), and in the 3b degree it amounts to 4 % (degree of damage 81 - 99 %>). In the 3a and 3b degrees of damage there are more infested than non-infested silver fir trees. Of all the examined trees 0.63 % were dead trees (0.19% infested with mistletoe). The intensity of mistletoe infestation varies considerably from forest office to forest office. In 12 forest offices the slightest infestation intensity is in the forest office Tršće (1.4 %) and Ravna Gora (2 %). These are followed by the forest offices Prezid (12 %) and Crni Lug (16 %>). Between one fourth and one third of the examined trees is infested on the area of the forest offices Fužine (26 %), Lokve (26 %) and Rijeka (28 %>). Between one third and a half of the examined trees was found in the forest office Mrkopalj (35 %) Gomirje (41 %) 558 |