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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   101
Do we use biomass as an energy source? If so, how do we use it?      
The Russian aggression on Ukraine and the related sanctions have again confirmed our dependence on fossil fuels: not only is their price soaring, but their availability is also questionable. Perhaps the current situation will accelerate the process of transition from fossil fuels to renewables based on water, wind and solar energy, thermal resources and biomass. In this sense, it may do more than all those climate conferences, because the fear of energy shortages exceeds the awareness of the need to preserve the earth from global warming. Thus, the goals of the Glasgow Climate Conference to reduce greenhouse gasses to 55 % by the year 2030 could be achieved ever earlier.
In terms of the protection of nature and the environment, it is calculated that wood as an energy source for heating a family house with 20,000 kWh annually emits 100 kg CO2 during combustion, gas emits 4,600 kg CO2, and fuel oil emits 5,600 kg CO2. Therefore, to generate the same amount of energy, the odds are 1: 9 in favour of wood.
With its available biomass, forestry can definitely help in the production of heat and electricity. Let us emphasise: with regular production at realistic regular annual cuts, with the use of biomass, which has until now remained in the forest, and with more intensive silvicultural treatments of cleaning and tending of stands, which become profitable as a new product carrying a decent market price, the potentials of biomass in the near future reach about 4.5 million tons annually, equalling 2.2 million tons of oil. From a professional forestry standpoint, these currently profitable treatments, which we often neglect due to lack of financial resources, would have an immeasurable importance for the quality of the forest, the value of its non-market functions and the insurance of sustainability, and in particular for the implementation of the Kyoto Protocol and the Graz Declaration, whose signatories we are.
Have we already written about this topic? Yes, we have, on several occasions. Browsing the Editorials from this column, we come across this topic with the same title in the Editorial from double issue 7-8/2010. In the previous paragraph, we also provided some information from that article. The excursion of members of the Croatian Forestry Association to the forestry and wood technology fair “Holzmesse” in Klagenfurt and the “Interforst” in Munich was also mentioned. Both these trade fairs were dedicated to the procurement and use of forest biomass. A business conference focusing on the topic “Biomass (electric and thermal energy), Biogas and Biofuels” has for years been held in Našice within the Croatian Biomass Day. The Croatian Forestry Association has discussed the issue of bioenergy at the thematic meetings of its Managing Board, annual symposia or within the activities of the CFA’s section Croatian Biomass Association. Let us also mention the scientific symposium “The production of renewable energy sources from agriculture and forestry”. We sell wood chips, but we could sell energy like the Austrians or the Germans do – for example, Austrian state forests own 30 cogeneration systems and sell KwH as a finished product, not a raw material. We can also mention the scientific conference “Forests, water and soil as the greatest wealth of the Republic of Croatia”, where we can learn something about thermal waters in which we also abound.
Regarding the production of pellets, the scientific article by Domac, J. et al, provides extensive information on the development of the domestic pellets market. In the year 2009, eight Croatian producers planned to produce 212,100 tons of pellets, but they only produced 92,000 tons, of which 98 % were exported and only 1,850 (2%) tons were sold on the domestic market. In addition to savings and a more environmentally friendly method of heating compared to conventional heating with firewood, it would also provide employment, especially in the domestic metal industry (stoves, pipelines, etc.). The author wonders: Where is the Energy Development Strategy?
If we asked ourselves what has changed in the past 12 years, the answer would undoubtedly be – something has changed, but things are not going in the right direction. At a gathering in Našice, the guest mayor of Güsing (Burgerland), who fully covers his electricity and thermal needs from renewable energy sources available in his region, called on mayors of cities and heads of municipalities, especially in rural areas, to make the use of biomass as an energy source their primary task. Despite numerous study visits to the Burgerland region, which is one of the best European examples of energy independence at the local level, no place in Croatia, even a small one, can boast of such a case. In 2011, we had the opportunity to see how the Swedish town of Östersund with about 50 thousand inhabitants, using biomass from the surrounding area (50 % forest biomass, 30 % wood debris from the wood industry, 10 % from old furniture and carpentry and 10 % from peat), had been producing heat and electricity for a decade, covering as much as 98 % of the total energy consumed by 10,000 households. Cogeneration plants have sprung up in Croatia, using favourable annual contracts for the supply of raw materials and energy incentives for the sale of electricity, but the local community has very little benefit from this. Moreover, part of the cheap wood raw material is turned into pellets, but these pellets are mostly used to heat inhabitants of other countries and not those of Our Beautiful Homeland. In both cases, it is only plant owners and sellers of produced energy and raw materials that are on the receiving side.
We can only hope that the current energy crises will clarify the views of those in charge and encourage them to start using all the wealth that Croatia has at its disposal.
Editorial Board

David Janeš, Andreja Đuka, Ivica Papa, Tibor Pentek, Maja Moro, Ivan Žarković, Tomislav Poršinsky  UDK 630* 686 + 463 (001)
Indicators of primary forest accessibility in different terrain categories      
Knowledge of the characteristics of the density and spatial distribution of forest roads in different bioclimates (terrain categories) facilitates further planning and design processes of future forest road networks. The basic parameters of forest accessibility based on primary forest roads were researched within twenty management units. The research was conducted in four bioclimates: 1. Common oak and floodplain forests, 2. Sessile oak forests of hilly terrain, 3. Submountainous beech forests and 4. Mountainous fir, beech-fir and spruce forests. The following parameters of forest accessibility were analysed: 1) forest road density and factor of forest area indentation, 2) average geometric timber extraction distance and road network factor and 3) primary relative forest accessibility. The obtained results indicate similarities and differences in the quality and quantity of the primary forest road network in each bioclimate.

Key words: forest roads; bioclimates; planning; terrain category; ArcGIS

    David Janeš  
    Andreja Đuka  
    Ivica Papa  
    PENTEK, Tibor      ŠL
    Maja Moro  
    Ivan Žarković  
    PORŠINSKY, Tomislav      ŠL
Kristijan Tomljanović, Marijan Grubešić, Danko Diminić, Milan Poljak, Jelena Kranjec Orlović  UDK 630* 156 + 451 (001)
Red deer (Cervus elaphus L.) damage on stands of narrow-leaved ash (Fraxinus angustifolia Vahl) of Middle Posavina      
Forest ecosystems are complex systems where it is often hard to predict and explain mutual activities and interactions of individual factors. Different species of big game make an inseparable part of these ecosystems. Game, particularly big ruminants and wild boar are in a constant interaction with the flora of the area they inhabit. Their positive and negative effects vary during different forest stand phenophases and depend on the forest stand age, presence and number of different game species,
availability of food, etc. The negative effects of big game on forest stands have been studied worldwide and in Croatia as well. The focus of this research was to analyse the bark damage induced by red deer on young trees of narrow-leaved ash. The research was conducted in two narrow-leaved ash forest stands situated in the Sava river basin in Croatia, where red deer is known to be present. The obtained results indicate that debarking (bark peeling) of young trees starts immediately upon the removal of the protective fence which is usually put up around forest stands during the regeneration period. Diameter at the breast height (DBH) of damaged narrow-leaved ash trees varied from 2 to 18 cm. In trees of greater diameter, new bark peeling didn’t occur, and damage induced in previous years became less conspicuous due to the formation of thicker bark layer. Bark damage was visible from the root collar (ground level) up to 190 cm of the stem height. With the increase of DBH (in the range from 2 to 18 cm), the girdling intensity, i.e., the cumulative damage from previous years increased as well. In some research plots the damage was visible on all narrow-leaved ash trees. Bark damage induced by red deer was not observed on the pedunculate oak and indigo bush, which were the two most common woody species in the researched area just after narrow-leaved ash. Conducted bark analysis didn’t indicate that the lack of nutrients, soluble sugar or minerals is the reason for the extensive bark peeling of the narrow-leaved ash bark.

Key words: narrow-leaved ash; tree damage; big game; red deer

    TOMLJANOVIĆ, Kristijan    ŠL
    GRUBEŠIĆ, Marijan      ŠL
    DIMINIĆ, Danko    ŠL
    Milan Poljak  
    Jelena Kranjec Orlović  
Mustafa Arslan, Arzu Ucar Turker, Isa Tas, Arzu Birinci Yildirim, Erva Ozkan  UDK 630* 423 (001)
Determination of some phenolic substances in six different populations of turkish hazel (Corylus colurna L.) leaves and comparison of phenolic fluctuation with water deficiency      
Turkish hazel (Corylus colurna L.) is one of the naturally grown hazelnut species in Turkey. It can be easily separated from other hazel species with its thick single stem and tall appearance. It can be used in afforestation and erosion control studies due to low demand for habitat and strong root system. It contains substances with high medicinal value in its fruits and leaves. Hazel leaves have strong antioxidant activity due to their high phenolic content. Objective of the study was primarily to determine the individual phenolic constituents of six different population of Turkish Hazelnut and then to evaluate the effect of water deficiency stress generated by irrigation regime on phenolic constituents and photosystem II activity on these genotypes. Grafted plants were produced by taking scions from six different populations of Turkish Hazelnut (Oğuzlar, Erenler, Merkeşler, Seben, Güney Felakettin and Pelitcik). The study was started when the grafted seedlings were 7 years old in greenhouse. During the experiment (June and July), two different levels of irrigation were applied (W1: the soil was fully irrigated to reach field capacity in each irrigation; W2: 50% reduction of W1 irrigation water). After the application of two different irrigation regimes, leaves were collected for each month, dried, extracted with methanol and then quantitatively analyzed and compared for individual phenolic constituents (gallic acid monohydrate, caffeic acid, rutin hydrate, luteolin-7-O-β-D glucoside, kaempferol, rosmarinic acid, myricetin, quercetin, coumarin and apigenin) by using high performance liquid chromatography (HPLC) coupled with a diode array detector (DAD). Generally, rutin, kaempferol and luteolin were dominant individual phenols in methanol extracts of Turkish hazelnut leaves. Pelitcik population was noticeable source of rutin and kaempferol in June, and the halved irrigation regime significantly increased the levels of both phenols in July. Similarly, the highest total phenolic content was observed in the Pelitcik population in June and the halved irrigation regime significantly increased the total phenolic content in both months in this population. It was also determined to what extent water deficiency physiologically
affects the quantum efficiency (Fv/Fm) of photosystem II activity through chlorophyll fluorescence technique in hazelnut leaves. Generally, Fv/Fm value decreased with water deficiency. This study showed that water deficiency stress generally caused an increase in phenolic constituents in Turkish Hazel leaves and they may be proper natural sources of phenolic constituents with abiotic stress applications in pharmaceutical and food industry.

Key words: Corylus colurna L.; quantum efficiency; phenol; Turkish Hazelnut; water deficiency

    Mustafa Arslan  
    Arzu Ucar Turker  
    Isa Tas  
    Arzu Birinci Yildirim  
    Erva Ozkan  
Ender Bugday  UDK 630* 261 (001)
A GIS based landslide susceptibility mapping using machine learning and alternative forest road routes assessment in protection forests      
Forestry activities should be carried out within the purview of sustainable forestry while reaping the benefits of forestry. Accordingly, the construction of forest roads through forests should be carefully planned, especially in protection forests. Forest areas in Turkey are generally widespread in mountainous and high sloping areas that are susceptible to landslides-landslide susceptibility is one of the most important criteria for the selection of protected forests. As such, it is important to evaluate detailed and applicable alternatives regarding special areas and private forests. The aim of this study is to determine alternative routes for forest roads in protected forests through the use of geographic information systems (GIS), particularly in areas with high landslide susceptibility. To this end, a landslide susceptibility map (LSM) was created using logistic regression (LR) and random forest (RF)
modeling methods, which are widely used in machine learning (ML). Two models with the highest receiver operating characteristic (ROC) and area under curve (AUC) values were selected, and ten factors (slope, elevation, lithology, distance to road, distance to fault, distance to river, curvature, stream power index, topographic position index, and topographic wetness index) were used. The best LSM modeling method was AUC. The AUC value was 90.6% with the RF approach and 80.3% with the LR approach. The generated LSMs were used to determine alternative routes that were calculated through cost path analysis. It is hoped that the susceptibility to landslides and selection of alternative forest road routes determined through the approaches and techniques in this study will benefit forest road planning as well as plan and decision makers.

Key words: forestry; alternative route detection; cost-path; random forest; logistic regression

    Ender Bugday  
Zdravko Dolenec  UDK 630* 148.2 https://doi.org./10.31298/sl.146.3-4.5 149
Dates of arrival of the Eurasian golden oriole (Oriolus oriolus L.) in decidious forest in relation to increase of local air temperature in NW Croatia      
Numerous regions worldwide are affected by Earth climate warming. Most studies of bird phenology in relation to global and regional climate change have focused on trends in arrival dates and breeding dates. The study investigates the results of phenological spring migration research on Eurasian Golden Oriole during a period of 26 years (1991–2016) in relation to average spring air temperatures (April–May) and year in deciduous forests (northwestern Croatia). Data is available for spring arrivals detected by the first song. Arrival date advanced significantly during the research period. According to the linear regression slopes, models suggested that in Eurasian Golden Oriole arrival date has advanced 6 days in period 1991–2016. Furthermore, average spring air temperatures (April–May) increased significantly during the study period. Furthermore, date of arrival was significantly negative correlated with average spring temperatures. My results provide evidence that warms spring has impacted spring migration arrival dates of Eurasian golden oriole of the deciduous forests in northwestern Croatia.

Key words: Eurasian Golden Oriole; Oriolus oriolus L.; spring migration; spring temperature; deciduous forests; NW Croatia

    Zdravko Dolenec  
Matija Bakarić, Ivan Martinić, Mario Šporčić, David Mijoč, Matija Landekić  UDK 630* 641
Entrepreneurial infrastructure and entrepreneurship in forestry of Croatia – possibilities and perspectives      
The introduction provides an overview of a wide range of definitions of entrepreneurship and a brief overview of the situation and issues through institutional and legislative review. The second chapter presents the key features of forestry entrepreneurship in the Republic of Croatia. The main indicators of improving services in the forestry sector through the use of entrepreneurial services are discussed. Emphasis was also placed on comparison with EU standards through small business. Subsection 2.1 provides an overview of entrepreneurial opportunities in the forestry sector with special emphasis on innovative activities in which young forestry professionals could find themselves in the business of improving existing products and services, new services and new products. The third chapter lists the elements of entrepreneurial infrastructure through their facilities and all assessed in Table 1 through a SWOT analysis which shows the characteristics of strengths and weaknesses as internal characteristics and opportunities and threats as external characteristics. Section 3.1 lists the entrepreneurial support institutions established under the Law of the Improvement of Entrepreneurial Infrastructure. Subsection 3.2 provides an institutional framework for entrepreneurship management through strategic documents and laws with their characteristics. Subsection 3.3 shows aid to entrepreneurs from the EAFRD Fund for Rural Development. Table 2 shows the types of operations intended for the forestry sector together with the business entities for which they are intended and the amount and intensity of support. Subchapter 3.4 shows the support provided by the Republic of Croatia for the development of entrepreneurial activities, primarily through the credit lines of the Hrvatska banka za obnovu i razvoj (HBOR) and HAMAG-BICRO. Table 3 shows the currently available HBOR credit lines which are used as a starting point for selecting the most applicable for the forestry sector. From the shown credit lines, three are compatible and potentially applicable in the forestry sector. At the same time, these lines are shown with their characteristics in Table 4. Furthermore, the Croatian Government Agency HAMAG-BICRO also encourages the establishment of the forestry sector through three models shown in Table 5 with its characteristics for a successful promotion of entrepreneurship. forestry. In the last chapter, instead of conclusions, the problem of the lack of mass of potential entrepreneurs, primarily from a population of young forestry professionals, is mentioned. This is due to the lack of consideration by forestry experts about entrepreneurship as an interesting option. The impetus for thinking about entrepreneurship is certainly the simplified establishment of a business entity and the growing number, although still an insufficient number of credit lines for newly established business entities.

Key words: innovation; economic development; start-up; supports

    BAKARIĆ, Matija    ŠL
    MARTINIĆ, Ivan      ŠL
    ŠPORČIĆ, Mario      ŠL
    David Mijoč  
    Matija Landekić