|ORIGINAL SCIENTIFIC PAPERS|
|Vukelić, J., Baričević, D., Drvenkar, D.||UDK 630* 188 (001)|
|Phytocoenological Characteristics of Beech Forests in Samoborsko Gorje pdf HR EN||531|
|Idžojtić, M., Pernar, R., Kauzlarić, Ž., Abramović, M., Janković, D., Pleše, M.||UDK 630* 442 + 582 (001)|
|Intensity of Infestation of Silver Fir (Abies alba Mill.) with Mistletoe (Viscum album L. ssp. abietis (Wiesb.) Abrom.) in the Area of the Forest Administration of Delnice pdf HR EN||545|
|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 %) and Skrad (49 %), whereas in the forest office Delnice a little more than a half (52 %) of the examined trees is infested with mistletoe. The highest percentage of infested trees was found in the forest office Vrbovsko (63 %).
In more favorable living conditions for silver fir trees mistletoe would be a part of biocenosis, and its presence would not represent a special problem to the host. According to the present state of distribution and intensity of infestation mistletoe can be considered one of the unfavorable biotic factors for silver fir trees.
Based on the distribution of infested and non-infested fir trees in degrees of damage from 0 (healthy trees) to 4 (dead trees) it was noted that mistletoe appears on physiologically weakened trees. The more mistletoe bushes there are on a tree, the more stress there is for the host tree under its influence due to lack of water; the tree weakens additionally under the influence of a combination of other unfavorable factors, it becomes non-resistant to secondary parasites and illnesses, and it can even die. The fact is important that with the increase of infestation intensity in an area, there is the trend of mistletoe spreading on less damaged silver fir trees, and it can be presumed that these trees will be in a greater degree of damage in the near future.
Key words: Viscum album L. ssp. abietis (Wiesb.) Abrom.; Abies alba Mill.; intensity of infestation; degree of damage; Croatian Forests Co. Ltd.; Forest Administration Delnice
|Starčević, M.||UDK 630* 423 + 181.3 + 188 (001)|
|The Effect of Precipitation, Flood and Groundwater on the development of Stands in the Forest Complex “Česma” pdf HR EN||561|
|Tomašević, A., Kulić, B., Španjol, Ž., Kružić, T.||UDK 630* 232.4 + 234 + 524|
|Development of Black Pine Stands (Pinus Nigra Arn.) and their Ameliorating Role in the Forest District of "Lonja-Biljin", Forest Office Rijeka pdf HR EN||579|
|Božičević, I., Radočaj, M.||UDK 630* 902|
|Forestry in the Region of Slunj pdf HR EN||597|
|Domac, J.||UDK 630* 931 + 238|
|Energy Sector Legal Framework for the Forest Biomass and the Renewable Energy Utilisation in the European Union and the Republic of Croatia pdf HR EN||609|