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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   415
Should there be concern over the future of human resources in forestry?      
For the past several years, the Faculty of Forestry and Wood Technology of the University of Zagreb has been promoting the faculty by visiting secondary schools across Croatia and by posting advertisements on websites. These activities were prompted by the reduced interest in enrolling in the only faculty in the country that educates experts in forestry and the wood industry. The justification of such measures has been confirmed by the fulfilment of enrolment quotas in recent years. In contrast to earlier periods, particularly the eighties and nineties of the 20th century and the first decade of the 21st century, when forestry itself was a motive for enrolment in the faculty by a larger number of candidates than needed, recent times have brought about changes that require efforts to make the profession recognized on the education and labour market. New generations of students find private entrepreneurship in forestry more attractive, compared to earlier preference for employment in the state company Croatian Forests Ltd. Probably an important part of the reason for this change was the business policy of Croatian Forests from 2012 to 2018 whereby there was a significant reduction in the number of workers of all profiles, which in turn made education in forestry less attractive. In addition, the average salary in a state-owned company, which is not significantly higher than the national average, also lessens interest in employment there. More recently, efforts have been made to attract new work force in the state-owned company by offering scholarships to students. The current age structure of the employees at Croatian Forest Ltd shows that the generation which started working at the company when it was established in the early 1991 is retiring. Will the lost years without timely recruitment and training of personnel, especially forestry engineers/masters and technicians, create problems in the business of this state-owned company?
The Croatian Forestry Association (CFA) has dealt with the topic of education and employment in forestry on several occasions. At the Days of Croatian Forestry, held in 1999 in Ogulin and Bjelolasica, one of the professional topics of the 103rd CFA Assembly was “Employment of forestry workers and development of entrepreneurship in forestry”. As part of the 109th CFA Assembly, at the Days of Croatian Forestry in 2005, a conference was held in Karlovac focusing on “Secondary-school and higher forestry education in Croatia with a special emphasis on the needs of forestry practice.” The Editorial of Forestry Journal 9-10 from 2012 addressed employment in forestry. It was stated that “for the past several years there has been no permanent employment of forestry engineers, but rather temporary employment or employment under various contracts.” This was a period in which graduates with a master´s degree in forestry thronged employment agencies and had a hard time even getting an internship. When the company Croatian Forests Ltd advertised for the post of district rangers at the beginning of 2015, as many as 220 candidates applied but only 79 were accepted. Not even ten years later, job advertisements for internship in traditionally forest regions such as Slavonia, do not attract young foresters with master´s degrees. According to the Editorial of Forestry Journal 7-9 from 2011 “… this issue of Forestry Journal states that the enrolment quota for the school year 2011/2012 for the profession of forestry technician was 290 students in 11 (!) secondary forestry schools, while at the same time there were over 500 unemployed forestry engineers registered with the Croatian Employment Service.” Obviously, there was discord between education and the labour market, as well as the inability of employers to recognize the need to hire young forestry technician who should replace the departing generations and become the bearers of operational forestry.
Another long-lasting problem, apart from an insufficient number of professional workers, is the lack of manpower to perform field work, from forest management and silviculture to logging operations. Modern technologies have compensated for the part of this problem, but some operations cannot be done without human labour. Will it become normal in the future not to implement management regulations because it is not possible to find adequate and trained workforce? All factors within the forestry profession, including the responsible ministry and the Ministry of Science and Education, should think about it and act on it.
Editorial Board

Marija Pandža, Milenko Milović, Vesna Krpina, Damira Tafra  UDK 630*182 (001)
The flora of the island of Rivanj and the vegetation of the macchia and forest of Rivanj and the Sestrice islets      
According to literature data and field research conducted in 2019 and 2020, there are 346 vascular native and non-native taxa with the ability to survive outside crops (309 species, 36 subspecies and varieties) on the island of Rivanj (3,615 km2). Including 84 taxa in cultivation, we state that the total flora of Rivanj numbers 430 taxa. Those in cultivation are not included in the flora analysis. During earlier research, 45 taxa were recorded, while 385 taxa are listed for the first time in this work. In addition to the flora inventory, a taxonomic, ecological and phytogeographical analysis was performed. The results are presented in Tables 1–4 and Figure 2. The composition of the flora is dominated by angiosperms, in which dicotyledons (73.99%) are significantly more common than monocotyledons (23.99%). The flora also includes two ferns and 5 gymnosperms. By the number of taxa, the most represented families are Poaceae (13.01%), Asteraceae s.l. (11.85%) and Fabaceae (8.96%). The spectrum of life forms is dominated by therophytes (43.93%) and hemicryptophytes (24.28%), while plants of the Mediterranean floral element (42.77%) dominate in the phytogeographical analysis, which indicates the climatic conditions and geographical position of the island of Rivanj. Four endemics and four endangered taxa (Lathyrus ochrus – critically endangered, Carex extensa – endangered and two vulnerable taxa: Orchis tridentata and Parapholis incurva) were recorded in the flora, as well as five orchid. Eleven invasive taxa were recorded in the weed and ruderal vegetation of the settlement (3.18% of the total flora of the island).
The investigation of the macchia and forest vegetation of the island of Rivanj and the islets of Sestrice was conducted in 2019 and 2020. The relevés were produced and analyzed according to the Braun-Blanquet method. Thirty relevés presenting the vegetation of the Quercetea ilicis and Pinetea halepensis classes were statistically analyzed and their dendrogram created. The results are shown in Tables 5–7 in accordance with the classic presentation regarding phytosociological relevés. Through the syntaxonomic analysis the Erico arboreae-Arbutetum unedonis Allier et Lacoste 1980 ex Foggi in Foggi et Grigioni 1999, Myrto communis-Pistacietum lentisci (Molinier 1954) Rivas-Martínez 1975, Pistacio lentisci-Juniperetum turbinatae Trinajstić 1987 ex Asensi, Díez-Garretas & Quézel 2007 and Myrto communis-Quercetum ilicis (Horvatić 1963) Trinajstić (1976) 1985 associations from the Quercetea ilicis class and the Pistacio lentisci-Pinetum halepensis De Marco, Veri & Caneva 1984 association. The autochthonous macchia and forest vegetation is mostly endangered by planted community of Aleppo pine on the islet of Mala Sestrica and on smaller areas on the island of Rivanj. North-west of the settlements on the Rivanj island a thick and impassable macchia grows. It is necessary to clear out the firefighting access paths and ban all activities that might cause fire.

Key words: phytosociology; the island of Rivanj and the islets of Sestrice; Northern Dalmatia; the Zadar archipelago; vascular flora

    Marija Pandža  
    Milenko Milović  
    KRPINA, Vesna    ŠL
    Damira Tafra   
Dževada Sokolović, Zerina Dupovac, Amina Karišik, Jelena Knežević, Velid Halilović, Jusuf Musić  UDK 630* 383 (001)
Damage on forest roads as a result of improper construction      
Forest truck roads are permanent buildings thet require certain kind of quality and standard for its building. Due to lack of financial resources, the quality of newly constructed forests truck roads in FBiH is becoming weaker with time.
The aim of this paper is determination of quantitative and qualitative features of newly constructed forest truck roads in the last 10 years in the area of the Managment Unit (MU) “Zujevina” , Forest Managment Region (FMR) „Igmansko“. The analysis of newly constructed forest roads was performed on the basis of data obtained by field measurements, which were then processed in the office and compared with the features prescribed by the Technical Regulations. In the last 10 years, two forest roads with macadam-type carriageway were built within the MU “Zujevina”, which increased the absolute accessibility of the managment unit, which now amounts to 9.45 m/ha and is significantly lower than the accessibility recommended for such areas and that is 15 m/ha.
By analyzing the technical and constructive features of the newly constructed forest road “Braćinac - Doljanske stijene”, it can be concluded that the average width of the road and the road shoulder width are within the intervals of the prescribed values.
In the length od 41% of the total length of the road, this road is characterized by deviations of the slope of vertical alignment in relation to the prescribed values. On 59% of the total length of the road, the measured longitudinal slope is in accordance with the Technical Regulations.
Side dithces were not built on the analyzed forest road, which is reason why atmospheric precipitation flows on the road surface, so in certain sections the quality of the road surface is poor and erosion occurs on the upper layer of the road.
The average cross slope of the road does not meet the prescribed values for that element. From the recordings of the cut slopes, we conclude that there are sections, about 9% of the total length of the road, which need to be cut, and sections in the length of 26% of the total length, which require construction work in order to adjust the slope of the cut slopes to the category of material in which they were built.
Analyzing the structural features, we obtained data showing that 67% of the pavement surface is undamaged, minor damage was recorded on 24%, while major damage was recorded on 9% of the total surface of the road.
Out of a total of five pipe culverts, four pipe culverts perform their function without interruption, while one needs cleaning of the entrance.
Field measurements were made only one year after the construction of the forest pavement and before the transport of wood assortments from the department that opens the road. The obtained results show that the low quality of construction and non-compliance with technical regulations results in accelerated deterioration of the road.
The damage recorded on the road can be attributed to the impact of increased atmospheric precipitation, which as a result of global climate change is becoming more frequent and should be taken into account when projecting and building forest truck roads.

Key words: forest truck roads; technical and constructive features; road maintenance

    Dževada Sokolović  
    Zerina Dupovac  
    Amina Karišik  
    Jelena Knežević  
    Velid Halilović  
    Jusuf Musić  
Vojislav Dukić, Srđan Bilić, Danijela Petrović, Goran Jović  UDK 630*810 (001)
Applicability of different regression models for estimation of merchantable wood volume of sessile oak (Quercus petraea (Matt.) Liebl.) in Bosnia and Herzegovina      
In Bosnia and Herzegovina, there are tariff tables used for estimating the volume of sessile oak trees in high forests, which were created on the basis of two-entry volume tables for oak trees from the area of Germany, authored by Schwappach in 1905. There are indications that the application of the aforementioned tariffs in forest management practice results in certain differences in the estimated amount of merchantable wood volume compared to the real situation. The material for creation of volume tables was the data concerning the measurement of 2,413 model trees in different habitat and stand conditions. A large number of widely used regression models was tested to equalize the volume of merchantable wood volume as a dependent variable in terms of the diameter at breast height and height of the tree as independent variables. Regression models such as Schumacher-Hall and Spurr II provide satisfactory accuracy, that is, they can be used to estimate the merchantable wood volume of sessile oak trees in high forests (pure and mixed) in the territory of Bosnia and Herzegovina, with a permissible deviation. By introducing the third variable into the model, diameter at seven meters height, the accuracy of the tree volume estimation increases significantly, but due to the significant increase in the volume of work on collecting the necessary data, this model is not suitable for use in forest inventories.

Key words: sessile oak; Smalian’s formula; merchantable wood volume; regression model; nonlinear regression

    Vojislav Dukić  
    Srđan Bilić  
    Danijela Petrović  
    Goran Jović  
Milan Drekić, Branislav Kovačević, Leopold Poljaković-Pajnik, Andrej Pilipović, Marina Milović, Vid Rađević  UDK 630*453 (001)
Impact of oak lace bug Corythucha arcuata on the height of pedunculate oak plants depending on the way of regeneration      
Oak lace bug Corythucha arcuata represents a new pest of oaks in Europe, introduced from North America in year 2000. Damage is caused by adults and larvae that feed on the underside of leaves. The paper presents the results of investigation of impact of Corythucha arcuata on pedunculate oak growth. The two variant experiment was established in 2019 and included the evaluation of the effect of oak lace bug on the height of the seedlings (i) grown under the shade of the adult trees after the intermediate felling and (ii) seedlings grown unshaded after the final felling. Both variants included eight plots of which four were treated with the insecticide thiamethoxam, while other four were untreated. Assessment of the intensity of the attack was performed in June, July and August in 2019, 2020 and 2021, while the height of the plants was measured at the end of the vegetation period in 2019, 2020 and 2021.
The results indicate significant decrease in the intensity of the attack on seedlings grown unshaded by the old trees. After first year, there was no difference in average height of the treated and untreated seedlings grown after the intermediate felling, while the difference was evident after second and third year. Such results indicate cumulative effect of the oak lace bug attack on the seedlings of the penduculate oak. On the other hand, during whole experiment, the differences between treated and untreated plant average height after the final felling were not evident.

Key words: oak lace bug; damage; Quercus robur; regeneration; height; seedlings

    Milan Drekić  
    Branislav Kovačević  
    Leopold Poljaković-Pajnik  
    Andrej Pilipović  
    Marina Milović  
    Vid Rađević  
Maja Cvek, Doris Šegota, Kaća Piletić, Gabrijela Begić, Maša Knežević, Dijana Tomić Linšak, Marina Šantić  UDK 630*145.7
Mosquitoes in Croatia, transmitting diseases, ways of prevention and control      
Today, the protection of nature and the environment is an integral part of economic and general social development. By raising awareness, thinking and acting proactively, we can count on the sustainable development of future generations. Nevertheless, changes in the ecosystem also have an impact on the number of individual insect species. Mosquitoes are cosmopolitan animals belonging to the family Culicidae. They are carriers of many pathogens that cause numerous diseases in humans and animals: Dengue fever, yellow fever, West Nile fever, tularemia, Japanese encephalitis, malaria, Zika fever, etc. The aim of this review is to summarize the current scientific knowledge about mosquitoes, their life cycle, the species present in the Republic of Croatia, the mode of transmission of microorganisms and the diseases transmitted by certain mosquito species in Croatia, and to present the most modern solutions for prevention and control of invasive vector species of mosquito Aedes albopictus using the technique of sterile males (SIT), which is considered one of the most environmentally friendly and developed methods of insect pest control.

Key words: diseases; Croatia; mosquito control; mosquitoes; sterile mosquitoes; vectors

    Maja Cvek  
    Doris Šegota  
    Kaća Piletić  
    Gabrijela Begić  
    Maša Knežević  
    Dijana Tomić Linšak  
    Marina Šantić  
Stanimir Živanović  UDK 630* 431
Determining the fire season by analyzing climatic conditions in northeastern Serbia      
The territory of Serbia is sensitive to forest fires, which endanger various systems and play an important role in shaping the ecosystem. The probability of the occurrence and spread of forest fires in the area of northeastern Serbia was examined, depending on the influence of climatic conditions. Changes in climatic conditions are investigated at the annual and monthly level of air temperature, precipitation and air humidity values recorded at three main meteorological stations (Zaječar, Negotin, Crni Vrh) in the area of northeastern Serbia. Changes in climatic conditions in the period 2009-2022 compared to the period 1961-1990 were analyzed, with an emphasis on 2012 and 2014.
The length of the average fire season was determined through a modified version of Thornthwaite’s evapotranspiration index. The fire season is longer in the area of Negotin and Zaječar than in the area of Crni Vrh. On the basis of the monthly humidity indices, a significantly longer fire season was determined in 2012 compared to 2014, as well as the multi-year period 1961-1990.
An analysis of the value of the Burning Index (B) for the period 2009-2022 was performed and a correlation was established with the data on the number of forest fires. The burning index in the area of northeastern Serbia is the highest during the months of July, August and September. Significantly higher values of the burning index are for 2012 compared to 2014, which is correlated with the occurrence of forest fires in this period.

Key words: Thornthwaite’s evapotranspiration index; Burning index; forest fire; fire season; northeastern Serbia

    Stanimir Živanović