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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   229
Are foresters the biggest problem of Our Beautiful Homeland?      
The negative media campaign directed against foresters, and particularly against the representatives of the company Croatian Forests Ltd, has been going on for several years and has gained in intensity in the past two years. It all escalated recently with the scandal concerning the wind power plant Krš-Pađene. The media rushed to smear individual and collective entities involved in the event. Based on impromptu analyses the company Croatian Forests was criticised for all kinds of things, including temporary non-payment of forest contributions to cities and municipalities (at the time when the state was at a complete standstill due to the coronavirus epidemics these earmarked funds could not be spent on the construction and maintenance of forest roads anyway), as well as raising a loan to boost the company’s liquidity. Namely, the company agreed to extend the payment period of the wood industry for the delivered raw material from 60 to 100 days from the date of issuing the invoice for all deliveries from the beginning of the year 2020.   Let us not even mention all those  remarks on the use of probably the most well-known parafiscal levy in Croatia related to non-market forest functions. There is not one entrepreneur or politician who has not requested the reduction or abolition of this levy as a way of helping the economy. Lay people are not even aware of the fact that the crisis plan of Croatian Forests envisages complete elimination of this form of financing forest management for 2020. At the time of the coronavirus crisis these are probably the best business moves aimed at preserving employment in the company, employment of the customers and suppliers, as well as the company’s liquidity. But who wants to read about this when negative news and scandals are much more interesting? Most people do not know either that at times of crises forestry has always taken care not only of  itself but also of others dependent on it. In all crises forestry has helped the wood industry, written off debts of various states and political systems reigning in these areas, but also borne the consequences of objective and subjective business risks of those working in the wood sector.
The power of the texts published on websites and social networks is enormous. They reach large numbers of readers in a very short time. The majority of the published texts feature bombastic headlines and sub headlines. Only when the whole text is read does it transpire what is the truth and what is not. Usually the content of an article is softened towards the end, but the whole article is read only by the most persevering reader, while the majority retain only the negative information from the headlines and the beginning of the text. Social networks are full of individuals and associations whose comments, often anonymous, create a negative image of the forestry profession. All these comments give an impression that foresters are one of the biggest problems of Our Beautiful Homeland.
Those better acquainted with the situation realize that forestry and agriculture are the pillars of survival in the remaining rural areas. Forestry, which is most represented in rural and less developed areas, provides a livelihood for employees of Croatian Forests, employees of numerous contractors in forestry and companies and crafts in the wood sector, and indirectly of all those who sell their products to wood companies. Forestry also guards and cares about the largest part of the ecological network in the Republic of Croatia. By protecting forests and forestland from fires in karst areas it forms an important link in the conservation of biodiversity in the state, but also creates a setting which helps the Croatian economic branch of particular interest - tourism. During the Homeland War it was forestry professionals who constructed roads needed to connect parts of the Republic of Croatia at the time when residents had to travel through neighbouring countries in order to reach their home country.
In our beloved homeland there are eight national parks and eleven nature parks in which forests constitute the basic phenomena. Basically, nature conservation has taken over the preserved areas for management from foresters. If these areas had not been managed according to forestry postulates and ecological considerations, we would not be able to boast of parks such as Plitvice Lakes, Risnjak, North Velebit and Mljet. In the karst part of Croatia, where the majority of protected parks are located, forests have never disappeared thanks to two and a half century long forest management. Present day generations do not know what forests looked like in earlier periods. The majority of the most valuable forests of pedunculate oak were completely cut down between the 1820s and 1920s. Today we witness the growth of new generations of managed forests, which are essentially the product of Croatian foresters. After World War Two the quantities of forests that were cut down almost equalled present day quantities because there were no other resources and the state needed the necessary financial means for rebuilding and renovation. Moreover, thanks to the wisdom and hard work of several generations of foresters, the present forest cover in Croatia amounts to 44 percent and forestland to 49 percent. Regrettably, most people do
not comprehend the concept of eternal forests, which are not always of the same age, because just like other beings they have their development stages. Their eternity extends through generations of forests. Cutting down old, mature forest stands opens the door to a new generation of a forest, and all foresters rejoice in it because it testifies to a successful change of generations and the survival of the forest in the same area. This transition is visible in lowland forests, but there are also mountain forests in which such an obvious transition is not striking, so it is less noticeable to observers.
Those less well informed or malicious do not know about or close their eyes to decades of pressures on the state forestry. These pressures are aimed at enabling individuals and companies to receive different benefits: in the past it was olive groves and vineyards, today it is the construction of wind power stations and grazing in vegetation-covered or bare forest areas. Croatian foresters staunchly adhere to the concept of sustainable management, under which they fight against reducing forested areas. Thus, if forests are sometimes cut down for conversion purposes as regulated by spatial plans, reduced forested areas are immediately replaced with new forests in another place. Although state forestry has often been thought as a hindrance to development, it has in fact defended lawful activities in circumstances in which some investors, as well as state institutions, have exerted pressure by speeding up the procedure in their favour without any legal basis. The company Croatian Forests Ltd, with all its strengths and weaknesses, is only a part of the overall picture in the Republic of Croatia. Personnel recruitment and management is the same as in other public companies and state-owned companies. Just like in any other profession, there are omissions and mistakes, but one things is always the same: the postulates of Croatian forestry have been tested and verified for over 250 years. Present-day activities of lesser quality in some forests are the consequence of various factors and they do not differ from mistakes taking place in all other professional spheres (is not it true that sometimes a surgical operation may go wrong, or a building can be poorly constructed or a piece of machinery badly assembled?). Even in the most recent case of the Krš-Pađene wind power station, Croatian Forests Ltd have done their homework well by collecting the debt to the investor for easement in the amount according to the regulations valid at the time of starting the investment. 
In most of its activities Croatian Forests Ltd are between the hammer and the anvil: on the one hand, there is constant pressure by users of wood resources for more felling and more produced and sold quantities, and on the other, there is growing pressure to protect habitats and species, which all makes production more complex and more expensive.
The relevant ministry, in addition to dropping the word forestry from its name at the end of 2011 for the first time after 1919, has also become an evil stepmother to its own child, since the line minister, as a one-member assembly of the company Croatian Forests Ltd, by his/her orders to the Company management acts to benefit all aspirants to receive all  kinds of products and services from forests and forestland. Thus, the most valuable logs are sold at negotiated prices which have for years been out of touch with market conditions, fuel wood and wood residues are sold under long-term contracts regardless of changed market conditions, and bare forest land, and even truffles, must be given over to anyone who wants them, even if legal regulations are not complied with. 
The Croatian Forestry Association frequently points out that politicization of the entire system is one of the biggest problems of our society. Entire company managements are changed by politics every four or fewer years and nepotism is an inherent part of the system. Managements installed by politics in this way are forced to carry out the orders of the same policies, even if they are illegal. This is how companies, in our case Croatian Forests Ltd, are dragged through the media as criminal organisations; even public protests are organized against them. Can we even guess how the employees, our colleagues who do their jobs responsibly and lovingly, feel?
All these events raise fears of the terrain being prepared for giving state forests for concession after the company Croatian Forests is declared incapable of forest management. There are many examples of concessions generating exploitation of forests without any investments in them. The majority of European countries with abundant forest areas have strong state companies which manage and guard state forests, their areas and the life in them.
This text does not aim to defend anybody in advance: someone’s innocence or guilt will be decided on by relevant institutions. In the state in which fruitless debates about the past are held, it is time to turn to the present in a more rational manner and not succumb to harangues and hysteria. Politics should loosen its grip and leave it to the profession to do what it knows best: in the case of forestry, it is the management of forests and forestland.
Editorial Board

Mario Božić, Filip Đureta, Ernest Goršić, Mislav Vedriš  UDK 630*569 (001)
Influence of a measurer and measurement errors on  measurement of a tree diameter      
A tree diameter at breast height (dbh) is a basic variable measured in forest inventory. Generally, it is measured with calipers whose arms have to be perpendicular to the beam. Therefore, caliper has to be rectified before measurement. Measurement should be performed in the way that caliper itself is perpendicular to the tree stem with arms and beam touching the tree without applying too much pressure to caliper arms. Measurer mistakes and failing to follow standard measurement procedures lead to errors that reflect in all inventory results (basal area, stand volume). Experience gathered while working with students and colleagues in practice, showed that measurement procedures sometimes significantly depart from required. Therefore, the aim of this research was to quantify and analyze known and observed dbh measurement errors.
For that purpose two sites in Zagreb Training and Forest research center were selected: one site in area of lowland oak and hornbeam forest stand and another in mountain area with mixed fir and beech forest. Total 282 trees (74 Pedunculate oak, 56 Common hornbeam, 76 Silver fir and 76 Common beech) in wide diameter range were measured. (Table 1). All selected trees were marked with a number before measurement.
On both research plots three measurers performed following diameter measurements using Haglof Mantax caliper: crosswise diameters at self-estimated breast height with (1a, 1b), crosswise diameters at marked breast height (2a, 2b), 10 cm above (3a) and 10 cm under the marked breast height (3b), at marked breast height point with caliper beam held apart from tree and normal pressure on the caliper arms (4a) and higher pressure on the caliper arms (4b) and caliper beam on marked point with caliper tips facing up (5a). Measurement group consisted of two measurers. One measurer preformed measurement and other was writing the data. Since measurers height can affect the placement of the calipers on the tree, so position of breast height of 1,3m was determined using measuring tape before beginning of measurement for each measurer. Marking of breast height point on the tree was made after measurement with self-estimated breast height. Collected data were analyzed using t-test and ANOVA with 0,05 significance level.
Results show that average differences between two crosswise diameter measurements at self estimated breast height are statistically significant for hornbeam (average difference 1 cm) and beech (average 1,7 cm). Fir and oak had less differences (up to 0,7cm) that were not proven statistically significant. (Table 2).
At marked breast height differences of crosswise measurements are as well statistically significant for hornbeam and beech. (Table 3). Comparison between average diameter difference at self-estimated
and marked breast height show statistically significant difference for oak and beech. Negative average values for all measured species suggest that measurers usually slightly overestimated breast height (Table 4). According to Figure 1 it is visible that crosswise diameter differences are mostly within ±2-3 cm (50% difference). Certain trees show difference up to 15 cm in crosswise diameters. At the same time, diameter differences between self-estimated and marked breast height are smaller than crosswise diameter difference. Figure 2 shows that there is almost no trees which are not elliptical with fir having the smallest values.
Diameter measured 10 cm under marked breast height expectedly resulted in statistically significant higher values for all tree species with 0,49 cm on average (Figure 4), and diameters measured 10 cm above marked breast height resulted in lower values being statistically significant for oak, beech and fir (Figure 5). The biggest difference is for oak trees.
When caliper beam was held apart from tree and normal pressure on caliper arms applied, results were -0,12 to -0,26 cm lower and statistically significant compared to readings at correct position (caliper beam on the tree). The similar results were achieved with stronger pressure on the arms but with higher negative values, as expected.
Measurement with arm tips facing up resulted with statistically significant lower average diameter reading for all measured tree species (Table 9). Moreover, Figure 4 shows that in comparison to diameter measured on marked breast height readings on the caliper scale were in range between -1,5 to +0,5cm with extremes ranging from -4 to +2cm respectively.
Differences between measurers were observed on self-estimated breast height and for crosswise diameters on marked breast height. Table 10 and Figure 5 show that diameter differences between measurer 1 and other two measurers have proven to be statistically significant for self-estimated breast height of fir and beech trees (forest stand on sloping ground) where measurer 1 in average measured smaller diameters. Further, with diameters measured on marked breast height, differences were significant between measurer 3 and other two measurers in the way that measurer 3 on average measured larger diameters (Table 11 and Figure 6)
Diameter measurement is the basis for volume estimation of individual trees and stand as well. Therefore, measurement errors have impact on volume estimation, so measurement is subjected to control and sometimes allowable measurement departures are prescribed. Omule (1980) mentions that in Columbia Forest Service allowable errors of 1% for dbh is allowed and Melson et al. (2002) states that allowable dbh errors are ±0,25 cm for trees from 12,5 to 50 cm, ±0,5 cm for trees from 50-100 cm and 0,75 cm for treesfrom 100-150 cm dbh. Measurer responsibility is to perform the measurement according to the rules and with highest possible precision.
As the results show, differences in diameters can be a result of eliptical trees (Table 2, 3 and Figure 1). On tree level, differences sometimes reach 30% of tree diameter (Figure 1). With increase of tree diameter the difference between two crosswise diameters increases as well (Figure 3). Also, measurement under or above actual beast height results in statistically significant positive or negative diameter values.
Results based on measured sample trees show that hornbeam and beech breast height measurement gives a significant difference in crosswise diameters as a result of sloping ground and geographic orientation. Turning the caliper beam towards the plot center can cancel out these measurement errors assuming an adequate sample size. Furthermore, on trees that are to be cut, the breast height should be marked (on the upper side of the slope). In this way measurement error for a single tree level would be reduced. Finally, this research points out the importance of following correct procedures while tree diameter measurement in order to minimize measurement errors which can affect accuracy of measured data.

Key words: diameter at breast height; measurement errors; bias; forest inventory

    BOŽIĆ, Mario      ŠL
    Filip Đureta  
    GORŠIĆ, Ernest      ŠL
    VEDRIŠ, Mislav      ŠL
Mario Šporčić, Matija Landekić, Ivana Bartulac, Ksenija Šegotić  UDK 630*309 (001)
Application of multicriteria AHP method in selection of wood harvesting system      
Decision-making, as a process of selecting some of the alternatives to solve a given problem, in forestry is extremely demanding because of the multiplicity and wide range of criteria involved in the decision-making process. Such interests and criteria cover a number of economic issues, social issues, environmental and ecological issues. The application of different multicriteria decision-making
methods in such situations can be an important and potentially good way of addressing many forestry issues and problems. Multicriteria decision-making has been present in forestry for more than 40 years, however, more significant application has begun in the 1990s and numerous, in the meantime published multi-criteria papers dealing with different forestry issues in various areas. In this paper, a multicriteria procedure – Analytic hierarchy process (AHP) was used to evaluate the existing timber harvesting systems in Croatian forestry. The AHP, introduced by Thomas Saaty (1980), is an effective tool for dealing with complex decision making. By reducing complex decisions to a series of pairwise comparisons, and then synthesizing the results, the AHP helps to capture both subjective and objective aspects of a decision. In this way it aids the decision maker to set priorities and make the optimal decision. By using the AHP method, the appropriateness of particular timber harvesting systems for the specific conditions of selected forest stand and planned production tasks (thinning) was evaluated. The study included a comparison of seven different timber harvesting systems, i.e. alternatives: 1) Logger and adapted farm tractor, 2) Logger and skidder with winch, 3) Logger and forestry trailer with crane, 4) Logger and forwarder, 5) Harvester and forwarder, 6) Logger and mobile tower yarder, 7) Logger and cable yarder on truck. The aim was to develop a model for multicriteria assessment of the suitability and effectiveness of particular timber harvesting systems and also demonstrate the possibilities of applying the AHP method, as well as other multicriteria methods in forestry. Based on the prepared questionnaire, i.e. examination of forestry experts and comparison of existing timber harvesting systems, according to the set criteria, the ranks of individual alternatives were determined and a decision proposal was made on the selection of optimal timber harvesting system for the foreseen production tasks and specific conditions of a particular forest management area. Given the defined technological-biological, economic, environmental, ergonomic, energy and aesthetic selection criteria, a system consisting of a harvester and a forwarder was evaluated as the most appropriate option. Designed multi-criteria approach offers more comprehensive bases for deciding on the most suitable technologies and means of work at many different forestry sites in Croatia. The research results can thus support forestry professionals in decision making and indirectly influence the selection and implementation of specific timber harvesting systems. The development and application of AHP and other multi-criteria methods in this regard can be valuable assistance at the strategic and operational level of decision-making in forestry.

Key words: timber harvesting systems; forestry; decision making; multicriteria models; AHP

    ŠPORČIĆ, Mario      ŠL
    Matija Landekić  
    Ivana Bartulac  
    ŠEGOTIĆ, Ksenija    ŠL
Ivana Vitasović-Kosić, Mara Vukojević, Sandro Bogdanović  UDK 630* 174+182(001)
First inventory of vascular flora of Matokit mountain (Biokovo massif, Croatia)      
The vascular flora of Matokit Mt (Biokovo Massif) in southern Croatia was researched in different vegetation periods from 2010-2015, and a total of 604 vascular plant taxa belonging to 86 families and 337 genera were found. The studied area has never been studied in the past and these are the first detailed floristic data about grasslands in different succession stages of Matokit Mt. Collected herbarium specimens (345 sheets) were digitalized and are available at the ZAGR Virtual Herbarium. The most dominant families were legumes (Fabaceae 9.9%), grasses (Poaceae 9.1%), daisies (Asteraceae 7.4%) and mints (Lamiaceae 6.8%). The analysis of life forms shows the dominance of hemicryptophytes (39.9%) and therophytes (26.2%) on Matokit Mt that indicates a high influence of the Mediterranean climate. A total of 36 endangered and 17 invasive plant taxa across the whole studied area were recorded. Endemic are 32 plant taxa (26 endemics in a broader sense and 6 stenoendemics) and they represent new site of Croatian flora. The occurrence of some very rare endemics (Cardamine fialae Fritsch and Erysimum croaticum Polatschek) in the flora of Matokit Mt is of special interest for the national flora.

Key words: flora diversity; endemic taxa; grassland succession; Vrgorac

    Ivana Vitasović-Kosić  
    Mara Vukojević  
    Sandro Bogdanović  
Ali Kemal Özbayram, Emrah Çiçek  UDK 630* 561(001)
Initial planting density experiments of narrow-leaved ash in Turkey: ten-year results      
Narrow-leaved ash (Fraxinus angustifolia subsp. oxycarpa Vahl.) is a source of valuable wood in Europe and plantations produce high yields in Turkey. Initial planting density plays an important role in plantation silviculture and affects the growth and quality of trees as well as establishment costs. This study aimed to determine the ten-year effects of initial planting density on tree growth and quality of narrow-leaved ash. In 2004, three replications of four initial planting densities (1111, 1667, 2500 and 3333 stem ha–1) were established in a randomized block design in Adapazarı, Turkey. After ten growing seasons, no mortality was seen in all of four planting densities. The initial planting density had no effect on mean stem diameter; however, with the initial planting density increase from 1111 to 3333 stem ha–1, mean tree height was significantly increased and live crown ratio decreased. The H/D ratios at planting densities of 2500 and 3333 stem ha–1 were 21% higher than at lower planting densities. Aboveground dry biomass increased with increasing initial planting density at the stand level, although individual tree sizes were similar. In general, tree form and branch characteristics were improved when initial planting density was increased. Results suggest that on lowland sites where intensive weed competition occurs, higher initial planting density at 2500‒3333 stems ha–1 is recommended for narrow-leaved ash plantations.

Key words: Growth; Fraxinus angustifolia; initial spacing; stocking; tree quality; Turkey

    Ali Kemal Özbayram  
    Emrah Çiçek  
Abdullah E. Akay, Michael Wing, Halit Büyüksakalli, Salih Malkoçoglu  UDK 630* 432 (001)
Evaluation of Fire Lookout Towers Using GIS-based Spatial Visibility and Suitability Analyzes      
Effective forest fire fighting involves alerting firefighting teams immediately in the case of a fire so that teams can promptly arrive the fire scene. The most effective way for an early detection of forest fires is monitoring of forest lands from fire lookout towers. Especially in fire sensitive forest lands, towers should be systematically located in such a way that fire lookout personnel can monitor the largest amount of forest land as possible. In this study, the visibility capabilities of lookout towers located in Köyceğiz Forest Enterprise Directorate (FED)in the city of Muğla in Turkey were evaluated by using Geographical Information System (GIS) based visibility and suitability analysis. The results of visibility analysis indicated that 77.12% of forest land were visible from the current towers. To extend the proportion of visible forest lands, locations of additional lookout towers were evaluated using spatial visibility and suitability analysis in which the tower locations were examined by considering specific criteria (i.e. distance to roads, elevation, ground slope, topographic features). Suitability analysis results identified five new towers in addition to current towers in the study area. The results indicated that visible forest lands increased to 81.47% by locating new towers, and increase of almost 4.35%. In addition, over half of the forests became visible by at least two towers when including five towers suggested by suitability analysis. The GIS-based method developed in this study can assist fire managers to determine the optimal locations for fire lookout towers for effective fire management activities.

Key words: Forest fires; Fire monitoring; Visibility and Suitability analysis; Köyceğiz

    Abdullah E. Akay  
    Michael Wing  
    Halit Büyüksakalli  
    Salih Malkoçoglu  
Damir Drvodelić, Milan Oršanić  UDK 630* 232.4+237
Planting seedlings of narrow-leaved ash (Fraxinus angustifolia Vahl) to recover dieback-affected forest stands      
This review article lists and explains the benefits of planting activities undertaken in late summer and early fall, as well as spring planting before vegetation begins. Both irregular and correct digging of the plant pit and irregular and correct planting of bare-root seedlings of narrow-leaved ash are described and shown with the original illustrations. The influence of soil compaction on seed germination, seedling development, morphological characteristics of the above and below ground part of seedlings and root system is explained. The disadvantages of container production of forest seedlings in pure organic medium such as black peat and the disadvantages of planting seedlings produced in the field are discussed. Properly and incorrectly planted fields of narrow-leaved ash seedlings have been described and shown with the original illustrations. Modern technology of nursery production of narrow-leaved ash seedlings in containers and the benefits of afforestation of seedlings of coated root are presented. Container production is semi-automated and planting in the field should be done exclusively with the help of planters, whose features and advantages are presented in the article. Innovative solutions for the construction of a planter are described with regard to the shape of the hole that they make. It is important that the holes made by the planters are not round or square / rectangular, otherwise the planting holes will break or burst away from the surrounding soil. In the case of planters operating a rhombus-shaped hole or dug-in planting pit, there is no cracking at the edge of the hole, but the hole shoots all over the profile, which is more favorable to the root system of the plant. The original illustrations show examples of poor and good geometric shapes of a plant pit. An example taken from the Brestje nursery in Sesvete (Croatian Forests Ltd.) is used to illustrate the technology of nursery production of container seedlings of narrow-leaved ash. The data from the substrate declaration used in container production of seedlings were compared with the results of our own chemical analyzes at the time of planting the seedlings in the field after one growing vegetation. The extraction of elements from the substrate samples is described and so is the preparation of samples for trace element content determination by the ICP-AES technique. The values ​​of the main substrate parameters obtained by the ICP-AES technique are presented, as well as the content of macro and micro nutrients in the substrate. The article presents the main morphological characteristics of container seedlings of narrow-leaved ash planted in the Lipovljani forest area in autumn 2017. In particular, the appearance of the washed root system of an average container seedling and its morphological analysis by means of WinRHIZO ProLA2400 (2005) scanner and software are presented. The causes of high mortality of narrow-leaved ash seedlings during afforestation in the Republic of Croatia are described, and concrete measures are proposed to improve the current situation in line with good forestry practices implemented in the countries of Central Europe and Scandinavia.

Key words: irregular planting; proper planting; container seedlings; peat substrates; root morphology

    DRVODELIĆ, Damir      ŠL
    ORŠANIĆ, Milan      ŠL