|ORIGINAL SCIENTIFIC PAPERS|
|Krpan, A. P. B., Poršinsky, T.||UDK 630* 360 + 662 (001)|
|The Productivity of Timberjack 1070 Harvester in Scotch Pine thinning pdf HR EN||551|
|Vučetić, M.||UDK 630* 111 + 431 (001)|
|Weather Conditions and Comparison of the Forest Fire Season 2001 With the Long-term Mean Values pdf HR EN||563|
|Anić, I., Oršanić, M., Detelić, M.||UDK 630* 429 + 231|
|The Revitalisation of Degraded Forest Ecosystem After the Dieback of Pedunculate Oak - a Case Study in the Kalje Forest pdf HR EN||575|
|Summary: The research deals with the structure of stands established over a degraded site after a catastrophic dieback of pedunculate oak stands in the forest of Kalje in the period 1983 - 1986. It is aimed at investigatinga) the structural properties of new stands established with rehabilitation treatments following the dieback of pedunculate oak stands, b) some possible impacts of dieback intensities in former stands on the structural properties of newly-established stands, c) the role of narrow-leaved ash in revitalising degrades sites. Research was conducted in experimental plots set up in the forest of Kalje in 1986, at the beginning of investigation of dieback causes and effects. The paper compares the results of 1986 and 1999.|
The plots were arranged by dieback intensities in former oak stands starting from low towards high intensity, or from Plot 1 to Plot 10. All experimental plots are 200 m2 in size and are distributed in the form of 100 m-long and 2 m-wide strips. All woody species in the plots were measured. If their breast diameters were less than 3 cm, they were classified (in terms of height) into height classes 25 cm wide. Three mean basal area trees were cut in each plot, and their age was determined and growth and increment analysed. All data were inserted into field manuals, while experimental plot positions were drawn into the Management Unit map. The average heights were calculated from height distributions of narrow-leaved ash, black alder and pedunculate oak. In order to have better perception of the extent of dieback in former pedunculate stands in the forest of Kalje, dieback intensities were analysed in selected compartments, in which experimental plots were established after the silvicultural procedure of restoration.
The canopy opening in the stands of pedunculate oak ensuing from extensive dieback in the 80s had the character of preparatory or seeding cut. The highest dieback intensities were characterised by an almost complete canopy opening and even by the final cut in some places. Abrupt light caused the soil to become weed-covered and swampy in places, with all the consequences mentioned in the introductory chapter. Silvicultural treatments of restoring the effects of dieback and gradually rehabilitating the degraded site included:
- preparing the site (draining stagnant water, removing weeds, loosening the soil, installing pipe drainage in the road to enable undisturbed circulation of flood water),
- tending the natural young growth occurring under the crown canopy during dieback and restoration (removing weeds, shrubs and advance regeneration, protection from game),
- artificial regeneration by planting seedlings of pioneer tree species and removing dry oaks with the final cuts.
The treatments were applied simultaneously in small areas within the same compartment. This required drawing detailed silvicultural plans with maps and schemes on a scale 1:5,000 or 1:10,000. The stand form was converted (substitution): oak stands were replaced with ash stands complemented with alders and other pioneer species. The newly-established stands were restocked and tended when needed.
These stands have currently reached the stage of the young growth. The stand canopies are closed and vital and contain sufficient number of plants per area unit. The results confirm past perceptions concerning the choice of tree species to rehabilitate degraded sites in Posavina. Narrow-leaved ash proved to be the most suitable species. In terms of participation, heights and vitality, it dominates other species in the stands. It has achieved heights between 5.18 and 10.19 m, and breast diameters between 4.29 and 8.12 cm. The average height increment in the past period ranged from 0.43 (min) to 0.72m (max.). No significant differences in the height increment were found in the plots.
For the moment, pedunculate oak does not play an important role in the stand structure. It occurs under the crowns of narrow-leaved ash in the developmental stages of seedlings and saplings. Attempts to favour oak with the practice of restocking have proved unproductive (plots 3 and 4). The share of black alder has decreased in the observed period. The heavy soils and weed-covered sites in the forest of Kalje do not seem to be as conducive for this species as they are for narrow-leaved ash. Additional research should be made to shed more light on this problem. Other species of pioneer character are the elements that fill the gaps in the stand canopies and increase their diversity. Depending on the height, cleaning or thinning treatments should be directed at ensuring an adequate share of "other" species in the species mix and not at removing them completely. This refers particularly to Tatarian maple, elm, spreading elm, common hornbeam, hedge maple and wild pear.
The analyses were made in the localities in which dieback in former pedunculate oak stands affected over one third of the volume, or 36 to 77 %. The results do not show a significant influence of dieback intensity of former oak stands on the structural characteristics of the present young growth. This means that for the moment, regardless of the degree and rate of dieback in the former stands, the young stands do not differ from each other. Accordingly, pioneer tree species should dominate in restorative silvicultural treatments undertaken to mitigate the consequences of intensive dieback (more than one third of basic volume) and sudden site degradation.
The results show that restoration was successful from a silvicultural aspect. New stands have been established which will fulfil their non-commercial and commercial role in the forest Kalje. Natural regeneration of pedunculate oak under the shelter of pioneer species points to a gradual site rehabilitation and a long-term transitional character of these stands. It should be stressed that this research is a contribution to the currently held attitude that a degraded site is lost for this tree species.
Key words: dieback; Fraxinus angustifolia Vahl; pioneer tree species; Quercus robur L.; site degradation; site rehabilitation
|Frković, A.||UDK 630* 156|
|On Croatian Deer Antlers pdf HR EN||589|
|Starčević, T., Dundović, J., Knepr, J.||UDK 630* 156 + 180|
|Forest Ecosystems Under the Circumstances of Separated Managements of Forests and Hunting Areas pdf HR EN||595|
|Majnarić, D.||UDK 630* 156|
|Bear Management as a Task of State Forestry pdf HR EN||601|
|Raguž, D., Grubešić, M., Starčević, T.||UDK 630* 156 + 945|
|The Tradition of Educating Forestry Personnel for the Needs of Hunting Management in the Republic of Croatia pdf HR EN||613|
|Vratarić, P., Tarnaj, I.||UDK 630* 156 + 135|
|Hunting Management in State Forests as Key Factor in the Transfer of Red Deer (Cervus elaphus) and Wild Boar (Sus scrofa) Breeding Stock pdf HR EN||617|
|Križaj, D., Vodolšak, M.||UDK 630* 156 + 931|
|Legal Provisions Regulating Game Loss and Damage from Game, and Protection Measures pdf HR EN||623|