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HR  EN   



Scientific-technical and professional journal
of Croatia Forestry Society
                         Issued continously since 1877.
       First issue of this web edition start with number 1-2/2008.
   ISSN No.: 1846-9140              UDC 630*https://doi.org/10.31298/sl

Portal of scientific
journals of Croatia
   Issued by: Croatian Forestry Society

   Address: Trg Mažuranića 11, HR-10000 Zagreb, Croatia
   Phone/fax: ++385 1 4828477
   e-mail: urednistvo@sumari.hr
   Editor in Chief: Josip Margaletić

Uredništvo   113
When Thomas Waitz, representative of the European Parliament and member of the Group of the Greens/European Free Alliance, published in his official page “a new report on deforestation in Croatia“, a report passed on by ViDrA– “Association of Veterans and Social Action“, this piece of news spread across the Croatian network media. On this occasion the portal Telegram.hr published an interview with Vesna Grgić, chairperson of Vidra Association. The Association’s Forum, called The Green Squad, was established, in their own words, “with the purpose of fighting against devastation of forests and forest land in the Republic of Croatia”.
The concern for common goods, which forests in the Republic of Croatia certainly are, is highly commendable. However, if we read accusations that refer mostly to the activities of the company Croatian Forests, one cannot but feel that there is a lot of misunderstanding of legal provisions and operational actions that take place in forest management. One of the examples of “disastrous forest devastation” mentioned in the interview was the possibility of a ban on logging in all forests for the period of 10 years and a comparison with Albania was given. There was no request from abroad for Albania to do so – it was a decision of the Albanian Parliament to impose a moratorium on cutting down forests for industrial purposes for the period from 2016 to 2025. The ban was implemented as a reaction to uncontrolled excessive logging, resulting in erosive areas clearly visible across the country. To compare this with the Republic of Croatia, which enjoys 256 years of organized forestry, is completely misplaced.
The basic misunderstanding generally displayed by the public refers to sustainable management using the shelterwood system, where at the end of the life cycle of an even-aged stand (the name itself denotes that the trees are of relatively even age), the mature forest, naturally with all trees, including thick ones, is replaced with a young forest, which is not always clearly visible outside the vegetation period. What is important is that the forest remains on the forested land: there is no devastation and no degraded forest stages (just as non-experts consider a young forest in progression a scrub; however, a scrub is an example of a reverse process – regression). The rejuvenation period, which lasts for up to 20 years and in the final cutting stage it may last for one or more years if smaller forested areas are treated, is in fact the birth of a young forest. We all know that in the human world a child is born after labour pains and growing up and turning an adult takes years. This can be compared with the emergence of a young forest and care for its development. The labour pains bringing forth a forest and its management take time. Not only can the forested area being regenerated be compared to a maternity ward, it is also a work site where special regulations apply, particularly those related to safety at work. Nature lovers who are angry about the damaged forest roads when passing through the forest being regenerated, should know that they are in a construction site and that they would not be able to move freely on the construction site of a building or a bridge. To draw a parallel, a forest construction site could be fenced off like any other construction site, banning access to the area.
It is unrealistic to expect that the condition of a forest, and indeed any other part of nature, can be conserved. Natural ecosystems are dynamic units that change constantly throughout time. In the Republic of Croatia, forests managed on a close-to-nature principle have undergone at least two, and some even three, complete lifecycles from their emergence to the final cut. This means that all stages have gone through this cycle, from a young forest only several centimetres tall, to an old forest with trees up to 30-40 metres tall. The average human lifespan today in our homeland of 78 years is just over half the lifespan of 140 years prescribed for pedunculate oak forests, and about three-quarters of the lifespan of 100 years prescribed for beech forests. It is normal that a resident or a visitor to a forest area overlooks the changes taking place in old forests which are not as drastic as those taking place when an old forest is replaced by a young forest. It is interesting that people rejoice when a new baby is born and is growing up, but are not happy when a new forest is born which foresters endeavour to make even better than the old one. An old proverb says “the world belongs to the young”. It is only logical that the same applies to forests. New forests will provide multiple benefits for new generations. Just imagine what it would be like of all present-day forests were two or more hundred years old (as is the completely protected forest of Prašnik, where very few old pedunculate oak trees are left, while younger hornbeam trees predominate below them, which in fact leads to the disappearance of the principal tree species). We would have forests full of diseased, useless trees. The wood industry would remain without the raw material for their work, and people would consequently be left without employment in the wood industry or without
numerous wood products. Another essential fact in the light of climate change is that the largest carbon sinks are created in forests younger than 140 years, after which carbon input decreases.
Another question to ask is why general concern about Croatian forests focuses only on state forests, while private forest owned by small forest owners, who make up one fourth of the overall forest complex, are the scene of all those actions that mimic the condition deplored by the Associations mentioned earlier. The age structure of the owners, unsolved property and legal relations, neglected and out-of-date cadastres and land registers, fragmented property, as well as inadequate legal solutions and the lack of organized guard service largely contribute to such a state.
The development of technology has provided various benefits and advantages to modern-day life, but also a number of disadvantages. Fast transfer of information has made it possible to gain an insight into different activities and professions, which has in turn created a false idea among people that they understand how all spheres of life function. Thus, many visitors to forests have become forestry experts and have been given an opportunity to express their views on the matter in the media. What is worse, such “experts” are believed more than the professionals who have been educated in the profession and have acquired experience through practice. Off-the-cuff and easily made accusations take the headlines and become the accepted truth, do denials are completely ignored and go unnoticed. Who is responsible for giving the public accurate and truthful information? There are individuals in every profession who do not work well or who make wrong moves, but this does not mean that generalisations can be made and conclusions passed on the basis of those few. Regrettably, today’s prevailing negativist journalism creates the conditions of distrust in any activity or profession, which is certainly not good and may become even worse in the future.
A young forest that will soon mature and become visible even to a non-forester’s eye, both on the frequently criticized Sljeme felling sites and all over Our Beautiful Homeland, will prove that the forestry profession exists and does its job thoroughly and successfully. In essence, this is the most important thing in the whole story. Such young and tended forests take up large areas, but are not recognized by a non-expert eye.
Editorial Board

Dino Hadžidervišagić, Azra Čabaravdić  UDK 630* 272 (001)
Importance and structural diversity of trees in a historical park      
This study investigated the importance of tree species and their families in the old historical park Ilidža, which has an area of 16.5 ha and is located near the city of Sarajevo in Bosnia and Herzegovina. The dendrometric variables of greatest importance (diameter at breast height, height, and crown diameter) were measured and the diameter distribution were determined and analyzed. The importance of tree species and their families was determined by an index of relative importance which was calculated using relative abundance and relative dominance. The results of this study show that the inversely proportional linear distribution of diameters is within acceptable parameters for historical parks, however there is an insufficient number of trees in the lowest and higher diameter classes. The most significant tree species having an index of relative importance greater than 10% were: sycamore maple (Acer pseudoplatanus L.), European ash (Fraxinus excelsior L.), largeleaf linden (Tilia platyphyllos Scop.) and Norway maple (Acer platanoides L.). These results of this study have a practical application in planning short-term measures for maintenance and care, as well as for the development of long-term strategies in order to achieve sustainable biological stability and other functionalities of urban green surfaces (ecological, biological, aesthetic, social, etc.).

Key words: historical park; urban trees; importance of species; diameter distribution; structural characteristics

    Dino Hadžidervišagić  
    Azra Čabaravdić  
Dušan Jovanović, Milan Gavrilović, Mirko Borisov, Miro Govedarica  UDK 630*902 (001)
Deforestation monitoring with Sentinel 1 and Sentinel 2 images – the case study of Fruška gora (Serbia)      
Forest and forest ecosystems have a big importance for the whole living world on the earth. Rapid deforestation poses a great danger and increases the effects of climate change. Large forest areas are cut down every year around the world and these activities need to be closely monitored to reduce their negative impact. Knowledge of valid and current geospatial data on forests and forest areas, obtained by interpreting the data by remote sensing methods has great importance for rapid response and
management of forest areas. Decisions that are based on outdated and insufficiently precise data can have negative consequences.
The researched area of Fruška gora is located in Vojvodina and occupies the northern part of Srem. Due to its natural properties, it enjoys the status of a special nature reserve. Pastures and fertile land, vineyards and orchards, decorate the slopes and lower parts of Fruška gora, while the areas above 300 meters above sea level are covered with dense, deciduous forests.
This paper presents a method of analysis of radar Sentinel 1 SAR satellite images, together with a combination of multispectral Sentinel 2 images, with the aim of identifying missing and newly formed forest areas, as well as assessing the usability of free, for everyone available radar satellite images for forest observation.
The described methodology is based on the selection of areas of interest, the selection of radar images for the chosen time epoch, image processing, the selection of training sets by combining radar and multispectral images. The classification of radar images was performed on the Cloud platform using the Random Forest classification algorithm. The study showed that in each analysed period from 2016 to 2019, the area under missing forest is larger in relation to the newly created area under forests, as well as the growing trend of new forest areas.
Estimation of classification accuracy for each observed time epoch was performed by calculating the error matrix and Kappa statistics, and the average classification accuracy was about 97%. Visual analysis and comparison of the obtained results with historical data confirmed the high accuracy of identification of missing forest areas.
The presented method showed that RF classification of free Sentinel 1 and 2 satellite images, can be used as a reliable and up-to-date data for forest monitoring with satisfactory quality and very quickly.

Key words: SAR; Copernicus; Random forest classification; forest monitoring; change detection

    Dušan Jovanović  
    Milan Gavrilović  
    Mirko Borisov  
    Miro Govedarica  
Boris Miklić, Anja Žmegač, Domagoj Trlin , Marko Orešković, Stjepan Mikac, Igor Anić  UDK 630* 111.8
Climate sensitivity of black pine (Pinus nigra Arnold.) chronology in the Northern Velebit      
Concerns for the possible consequences of climate change and their impact on the Mediterranean underline the need for a better understanding of climate variability throughout history, especially beyond the period covered with instrumental measurements. In order to improve the spatial and temporal coverage of the Croatian Mediterranean with climate data and to better understand the impact of climate change on tree growth, this first dendrochronological research was conducted in the area of ​​Northern Velebit. Results of the 274-year-old black pine chronology studied here indicate the main limiting factor in the growth of black pine trees is lack of moisture in the summer period. The correlations between the chronology of tree growth and the amount of summer precipitation from 1954 to 2015 are significant and positive (R = 0.60, p = 0.0099) and stable over time, with the possibility of climate reconstruction relatively far into the past for the area of ​​the northwestern Dinarides open.

Key words: black pine; northern Velebit; dendroclimatology; dendrochronology; climate change

    Boris Miklić    ŠL
    Anja Žmegač  
    Domagoj Trlin   
    Marko Orešković  
    MIKAC, Stjepan    ŠL
    ANIĆ, Igor      ŠL
Jelena Kranjec Orlović, Ida Bulovec, Milivoj Franjević, Damjan Franjević, Josip Skejo, Marin Biliškov, Danko Diminić, Boris Hrašovec  UDK 630*232.3 + 442
Preliminary results on narrow-leaved ash (Fraxinus angustifolia Vahl) and green ash (Fraxinus pennsylvanica Marshall) seed entomofauna in Croatia      
Native narrow-leaved ash (Fraxinus angustifolia Vahl) and introduced green ash (F. pennsylvanica Marshall) are two most common ash (Fraxinus spp.) species in Croatian lowland forests, taking a significant place in these ecosystems. In the recent past it has been observed that narrow-leaved ash seed yields have reduced, emphasising the importance of good health status of those collected, as they are used for seedling production and consecutive regeneration of forest stands or afforestation. Given that insects could be an important factor affecting ash seed health status, the aim of this research was to gain insight into the species being present and their frequency in the ash seeds. In total 2.500 narrow-leaved ash and 1.000 green ash seeds from seven different locations were screened for insect presence. Analysed seeds were categorized as undamaged, insect damaged or empty, and observed insect specimens were identified by morphological and molecular genetic analysis. Green ash seeds revealed higher insect infestation in comparison with native ash species, with weevil Lygniodes bischoffii being the most numerous pest found. Narrow-leaved ash seeds were mostly occupied by the native weevil species, L. enucleator. Besides these pests, larval, pupal, and adult stages of parasitoid wasps (Hymenoptera) and larval stage of the seed eating moth Pseudargyrotoza conwagana (Lepidoptera) were found in both ash species. However, given that pests detected in this study prefer urban areas or were present in a very small number of seeds, where they were often followed by parasitoids, it can be concluded that insects currently do not have a significant negative impact on the reproduction of narrow-leaved ash and green ash in forest stands.

Key words: ash; seed damage; weevils; Lygniodes; parasitoid wasps; Pseudargyrotoza conwagana

    Jelena Kranjec Orlović  
    Ida Bulovec  
    FRANJEVIĆ, Milivoj    ŠL
    Damjan Franjević  
    Josip Skejo  
    Marin Biliškov  
    DIMINIĆ, Danko    ŠL
    HRAŠOVEC, Boris      ŠL
Mirjana Stevanov, Albina Tarjan Tobolka, Ljubomir Kljajić, Martina Kičić, Max Krott  UDK 630*903
Analysis of conflicing interests on the example of the special nature reserve in Serbia: empirically analytical approach      
This study, based on modified Schusser´s sequential method, was conducted from August 2017 to August 2018 with the aim of using accessible and familiar case example from Serbia to verify the claim of forest policy science - that users, their interests and potential conflicts of interest can be comprehensively identified and analysed while applying empirically analytical approach. On the example of special nature reserve Koviljsko-Petrovaradinski Rit the intensity of user´s interest is assessed based on qualitative content analysis and critical reasoning in combination with the techniques of triangulation, induction and deduction. By entering the estimated intensity of user interests into the analytical sheme (users categorized as forest owners- state/province and private, forestry employees, enterprises/institutions and citizens), the first conflicting zone was identified between the very strong interests in forest utilization (priority of profitable timber harvesting) and the interest field comprising the very strong and strong user interests for nature conservation. In addition, the state/province (public enterprise Vojvodinašume) is in an internal conflict, having (also) a very strong interest in wood production (creating revenues) on the one hand and in nature conservation on another. In order to balance them (towards the general social interest), the state/province has an advantage of being in the position to look internally for a solution, but the analytical scheme also shows how potential changes could trigger conflicts with other users (wood industry if protection is increased or nature protection actors if logging intensifies). The current solution of protection zones, divided into strict protection 6%, active protection 29% and profitable use of wood 65%, reflects the actual compromise package between the state/province andinterests of remaining users, which will last as long as the state/province is in the position to support it with available political means.
Whereas individual discourses take into account only partial aspects, the current approach has provided a comprehensive insight into Rit´s actors and interests. Methodological set-up of existing theoretically-based analytical categories has offered conclusions relevant for further research, forming at the same time a strong basis for more active communication of results with practice: users can more clearly perceive each other’s positions and evaluate own abilities to act, while searching for the implementation concepts that work in practice.

Key words: interests; conflicts; protected areas; forest policy; Serbia

    Mirjana Stevanov  
    Albina Tarjan Tobolka  
    Ljubomir Kljajić  
    Martina Kičić  
    Max Krott  
Erol Akkuzu, Mustafa Şahin, Abdullah Ugiş, Ebru Bal  UDK 630* 453
Assesment of trap color and trap height above the ground on the capture of Ips sexdentatus and Thanasimus formicarius      
The six-toothed pine bark beetle Ips sexdentatus is one of the most devastating bark beetles of Eurasian pine forests. Pheromone traps are used to monitor and control Ips sexdentatus populations. In this study, the effect of trap color and trap height on the capture of Ips exdentatus and its predator the ant beetle Thanasimus formicarius was investigated. The research was conducted in Pinus sylvestris stands within Yayla Forest Enterprise Chief (Kastamonu-Daday) in Turkey. In the study area, 25 Scandinavian type three-funnel traps of 5 different colors (yellow, white, green, black, and red traps with five replications) were used. Traps were placed at the same height, 1.5 m above ground. For the second part of the study, a total of 20 traps (5 per height category) was placed 1.0 m, 1.5 m, 2.0 m, and 2.5 m above ground. Traps were controlled at intervals of 7-10 days and captured Ips exdentatus and Thanasimus formicarius were counted. The results of the study were as follows: 1) Significant differences in the number of captures by trap color, and 2) No significant differences in the numbers of Ips sexdentatus and Thanasimus formicarius captured between the trap heights.

Key words: six-toothed pine bark beetle; ant beetle; trap height; trap color; pine

    Erol Akkuzu  
    Mustafa Şahin  
    Abdullah Ugiş  
    Ebru Bal  
Damir Barčić, Vlado Habjanec, Željko Španjol, Mario Šango  UDK 630* 111.5 + 421
Analysis of raising windbreaks on the mediterranean karst of Croatia      
Windbreaks are established as barriers of rows of trees or shrubs that are planted to reduce wind speed, reduce evapotranspiration, protect against aeolian erosion, while being used directly to protect crops and plantations and provide favorable habitat conditions. One of the essential preconditions for the success of belt raising is the use of indigenous species that are adapted to habitat conditions. Technologies and protection procedures can be focused on biological-technical procedures of afforestation and raising plantations with the aim of mitigating wind gusts. The goal of windbreaks and raising plantations with different species is shown in the following figures (Figures 3,4,5,6,7). The choice of plant species for raising plantations is conditioned by different climatic zones, biological and ecological characteristics of the species, but also the composition with other elements of the landscape. An important feature of windbreaks is their wind permeability and impact on wind speed. Permeability depends on the habitus of the plant, and the type of trees and shrubs. The density of the windbreak changes its impact and effectiveness; the permeable belt ensures a balanced distribution as part of the wind skips it and part passes through the belt. The wind protection is placed in the direction of the main wind. Technical wind protection procedures include the construction of barriers made of building materials such as brick, stone, timber, glass, hard plastic or a combination of several types of materials (Figures 1 and 2). Biological procedures in terms of species selection and consideration of habitat conditions are much more complex. All this in the context of frequent changes in the “wind structure” in the karst area. Belt lifting can be differentiated according to purpose and expected performance as follows: impermeable belt, semi-permeable and permeable belt. The establishment of windbreaks primarily reduces wind strength and reduces its speed. In this way, the climatic extremes associated with the stormy wind are alleviated (the karst is primarily a bora) and it affects the microclimatic conditions, which can ultimately ensure the protection of agricultural and forest land.

Key words: wind; permeability; microclimate; erosion; soil protection

    BARČIĆ, Damir      ŠL
    Vlado Habjanec  
    ŠPANJOL, Željko      ŠL
    ŠANGO, Mario    ŠL