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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   305
The effects of stormy weather on forests      
It took only a few hours, and in some localities a short fifteen minutes, for the wind of stormy and almost hurricane force to destroy the hard work of generations of Croatian foresters on the stretch from the Slovenian border to eastern Slavonia, home to the commercially most valuable forests in our homeland: forests of pedunculate oak. It was these forests that took the severest blow. July 19th of 2023 will be remembered for misfortunes just like those winter days in 2014 and 2017, when ice and wind inflicted enormous damage on the forests in Gorski Kotar. The highest recorded wind speed in the Županja area was 180 km per hour. Historically, the highest recorded wind speed so far, amounting to 260 km per hour, was caused by a tornado in the surroundings of Novska in 1892, when 150 thousand oak and beech trees perished. The witnesses of this year´s storm were astounded by the power of nature, while the consequences resemble the cataclysm similar to that of an atomic bomb blast. Centuries-old forests of pedunculate and sessile oak, as well as beech, were turned into kindling and were flattened into cones. Although the storm led to human casualties, they did not occur in forested areas due to a set of fortunate circumstances (the thunderstorm occurred in the afternoon after working hours, so the forests were empty of people). The trees in alleys and parks in settlements posed a greater threat. More and more frequent extreme weather events leave a negative impact on the forest wealth in Croatia, but also in the rest of Europe. However, in spite of the evident effect of weather phenomena on the overall life, there are still sceptics who do not believe in human influence on climate change. For more than half a century there have been resolutions aimed at reducing the negative effect of the development of modern civilisation, primarily on the increase of carbon in the atmosphere and the rise in temperature. Regrettably, those who contribute the most to these negative trends, and these are primarily the richest countries in the work, are still not prepared to renounce comfort and the race for profit to the detriment of the entire planet Earth. The initial estimates of forest damage in state forests of Croatia amounted to over a million cubic metres. Subsequent field inspections increased damage to one and a half million cubic metres. Financial damage has so far been estimated at 100 million euro. There are no estimates of damage in private forests as yet, but damage is most probably high as well. More accurate data on damage will be established only after all the inflicted areas have been inspected and aerial surveys of the forest areas have been completed. The first thing to do was to clear public roads, which could not have been done without the help of forestry operations. This is where the state company Croatian Forests Ltd again stepped in with their readiness and capacity to help the community restore the safest possible transport in forest areas. There is arduous work ahead on clearing forest roads, and even more importantly, several years of work on repairing damage and restoring forest stands. Older stands, especially those in which shelterwood cuts were started or which were on the brink or regeneration, suffered the severest damage. Regular forest management activities were considerably disrupted by this disastrous event, while forest ecosystems of oak were additionally damaged by several years of dry periods and the negative impact of the oak lace bug, leading to a worrying long-lasting absence of acorn yield. It is questionable how regeneration will be undertaken in the light of a series of negative factors that primarily affect lowland ecosystems. The great damage inflicted on the wood mass will significantly reduce the financial value of sold products, which will mostly end up as stack wood and fuelwood. Decreased yields and increased costs require financial support of the state, similar to the support provided by the Federal Republic of Germany. Croatia´s membership in the European Union should also provide a positive aspect after this unprecedented weather disaster in repairing the damage to the constitutionally protected forest resource, whose positive role in mitigating climate change is gaining increasing importance. It is necessary to receive overall help from the relevant ministry both in financing the restoration and in simplifying legal regulations pertaining to such circumstances. A more positive media support and broader monitoring of unparalleled damage to forests is also needed. After this disaster, the public view of urban forestry and the negative attitudes towards removing dangerous and potentially dangerous trees from tree alleys and parks will probably change for the better.
Editorial Board

Darko Bakšić, Nera Bakšić, Daniel Krstnošić, Nikola Pernar, Ivan Perković, Stjepan Mikac, Vibor Roje, Branimir Krtalić  UDK 630* 114.3 (001)
Forest floor and soil properties of silver fir and european hop hornbeam forests (Ostryo-abietetum /Fukarek 1963/Trinajstić 1983) on Biokovo mountain      
Climate change is affecting the availability of resources and conditions critical to the life and survival of forest communities and the species that inhabit them, especially at the edges of their distribution. Numerous studies indicate that fir forests are threatened by climate change, especially at the southern edges of their range where the negative effects of warming are more pronounced.
The aim of this study was to determine for the first time for the thermophilic and southernmost fir and hornbeam forests (Ostryo-Abietetum) in Croatia the physiographic characteristics of the forest floor and soil, as well as the content of heavy metals in topsoil layer, and to compare the obtained data for the forest floor and soil with data for other fir communities in Croatia. These forests grow from 850 m to 1150 m a.s.l. on the continental slope of Biokovo Mountain on a characteristic sinkhole relief which influences the mosaic arrangement of soil, vegetation and forest floor.
Field observations in a number of sinkholes have shown that in summer (the dry and hot period) cold air flows in from caves and cracks and creates specific microclimatic conditions in the sinkholes that are favourable for fir and could be a key factor for its survival.
At the bottom of the sinkholes, fir trees dominate, rockiness is less pronounced and Mollic Leptosol and Leptic Cambisol alternate. The forest floor mass (load) is higher. On the other hand, at the edges of the sinkholes, the rockiness is more pronounced, the soil is either very shallow (Mollic Leptosol) or absent, and the forest floor mass is lower. Thermophilic tree species dominate, while firs are sporadic or absent.
Considerable amounts of forest floor and carbon stocks were determined in the fir and hornbeam forests, ranging from 2.86 kg m-2 to 11.59 kg m-2 and 1.13 kg m-2 to 4.89 kg m-2, respectively, with high spatial variability. According to the physiographic characteristics of the surface layer of the soil, fir and hornbeam forests are grouped together with the beech-fir forests of the northern Velebit and Gorski kotar, indicating the dominant pedogenetic influence of the (carbonate) parent substrate. The basic limiting factor of the soil of fir and hornbeam forests is its shallow depth. Elevated to very high content of the heavy metals Cu, Pb, Zn, Ni and Cd were found in the topsoil.

Key words: silver fir; soil; forest floor; European hop hornbeam; climate change

    BAKŠIĆ, Darko      ŠL
    MARKOVIĆ, Nera    ŠL
    KRSTONOŠIĆ, Daniel    ŠL
    PERNAR, Nikola      ŠL
    PERKOVIĆ, Ivan      ŠL
    MIKAC, Stjepan    ŠL
    Vibor Roje  
    Branimir Krtalić  
Tomislav Poršinsky, Zoran Bumber, Zdravko Pandur, Andreja Đuka  UDK 630* 312 (001)
Forwarder’s working range – from modeling to support for operational application      
In the example of an eight-wheeled forwarder, a simulation model is presented for assessing the mobility of the forwarder when transporting timber uphill and downhill. The presented model shows the changes in forces during timber forwarding by a nominally loaded forwarder due to a wide range of changes in influencing factors: 1) the slope of the terrain, 2) the direction of timber forwarding, and 3) the soil bearing capacity expressed by the cone index. By incorporating the criteria/limitations of timber forwarding derived from previous research, the forwarder mobility model gains practical meaning; that is, the theoretical approach brings the reality of timber forwarding closer. The mobility model shown is based on easily measurable or available data but also on the position of the centre of gravity, which is relatively easy to determine by the shown method of lifting the forwarders’ axle with the use of portable scales and is usually unavailable to read in the manufacturers’ catalogue. All known criteria/restrictions of mobility of forest vehicles are primarily related to their movement uphill. The limitation of the skidder’s mobility when skidding timber downhill has been firmly determined, while there are no limitations in the literature for forwarding timber downhill. Gradeability of a nominally loaded forwarder downhill, where the thrust force takes the value of zero, did not prove to be a good indicator or a limitation of timber forwarding. Determining the mobility limitations of the forwarder during timber forwarding downhill will be a research challenge in the future.

Key words: forwarder; centre of gravity; axle load

    PORŠINSKY, Tomislav      ŠL
    BUMBER, Zoran    ŠL
    Zdravko Pandur  
    Andreja Đuka  
Željko Španjol, Ivana Gašparović, Marko Vučetić, Dunja Zbiljski, Milan Vojinović, Vedran Sušilović, Ivan Ljubić, Katarina Korov, Boris Dorbić  UDK 630* 934 + 187 (001)
The biological and ecological characteristics of an special forest vegetation reserve Kočje - Korčula island      
The natural phenomenon of Kočje, was declared as a special reserve of forest vegetation in 1962, while its main phenomenon is a forest of hundred-year-old holm oak trees (Quercus ilex L.). It is a reserve of seed production with some sedges. Apart from it´s vegetation , Kočje has number of geomorphological forms. The forest of this reserve is classified as a forest of holm oak and black ash. The paper presents the results of extensive research conducted in the first half of 2015, which included structural, vegetation and microclimate measurements. The structural survey of the trees was carried out in the entire area of the reserve, and the vegetation and microclimatological research included 7 test plots.
The results showed that the inventoried holm oak trees (140) show a constant decline in vitality, which is quite understandable and related to their age and most of numerous species are in the stage of ponics and saplings: Laurus nobilis and Viburnum tinus, while holm oak predominates in the upper layer. With regard to the structural tables of the stands on experimental plots 1.-7. (tables 2-8), as well as the total amount of wood stock, it is conformed that the closed part of the reserve’s forest is still in the stage of high holm oak forest.
Phytocenological recordings (table 12) are showing that there is an heterogeneity of cellular conditions, since, in addition to the typical species of the association Fraxino orni–Quercetum ilicis Horvatić (1956) 1958 (Black oak and black ash forest), depending on geological-morphological, hydrological, pedological and microclimatic conditions, additional species which are not typical for forest vegetation. Primarily ferns, rock vegetation, mosses, etc. The vegetation cover in Kočje reserve is anuniform. In the central part where old holm oak trees predominate, the tree layer coverage is 90-95 % (100 %), bushes cover 30-100 %. The coverage of the layer of ground growth is also different and depends on the coverage of the layer of bushes and trees, so it is from 5-80 %. In the reserve, we find a thick layer of undecomposed leaf (2-5 cm), and in “pockets”, scraps between rocks, (10-15 cm). It is mostly applied by water during heavy rains. The microclimatic research has confirmed that the fluctuations of microclimatic elements (temperature and amount of light) depend on the degree of assembly of the stand in the layer of trees and bushes and the geomorphological conditions on the surfaces (stone corridors, arched and narrow passages, boulders, obstacles, etc.).

Key words: Kočje; special reserve of forest vegetation; holm oak; vegetation; measurements

    ŠPANJOL, Željko      ŠL
    Ivana Gašparović  
    Marko Vučetić  
    Dunja Zbiljski
    Milan Vojinović  
    Vedran Sušilović
    Ivan Ljubić
    Katarina Korov
    Boris Dorbić  
Dragana Skorup, Miroslav Vujasinović, Goran Marinković, Ilija Grgić, Boban Miletić  UDK 630* 615 (001)
Assessment of forest resources based on Sentinel-2 images – case study Derventa, BiH (Cadastral municipality of Brezici)      
The management of forest resources is complicated due to the complete lack of maintenance and disorganization of the land administration and survey that are decades old. Modern, unconventional monitoring systems are used with the aim of improving the existing records systems and creating a clearer insight into the state of forest resources. This study provides an example of the use of one such system, Sentinel-2. Using the R programming language, the multispectral Sentinel-2 images were classified by the Random Forest classification algorithm. Following the completion of the classifications, the accuracy of the classification was evaluated using the error matrix and the Kappa value. An analysis of forest resources for one cadastral municipality was accomplished using classified rasters and data from the Real Estate Cadastre Database. Based on the data analysis, major changes are visible in terms of the abandonment of agricultural land and its conversion into a certain form of forest vegetation. Furthermore, based on these data, the study demonstrates changes that can be monitored in shorter time intervals. Sentinel-2 images can be used to determine forest expansion, based on the aforementioned analyses, resulting in a clearer and better representation of existing forest resources that are unknown due to outdated and unreliable land administration systems.

Key words: Sentinel-2; Real Estate Cadastre Database; Random Forest; forest

    Dragana Skorup  
    Miroslav Vujasinović  
    Goran Marinković  
    Ilija Grgić  
    Boban Miletić  
Branislav Trudić, Biljana Kiprovski, Saša Kostić, Srđan Stojnić, Marko Kebert, Aleksandar Ivezić, Andrej Pilipović  UDK 630* 165 (001)
Are oxidative stress screening tests enough for small scale Quercus robur genetic monitoring?      
Although being present much widely in terms of its geographical distribution, pedunculate oak (Quercus robur L.) represents one of the crucial species in forest ecosystems in South Eastern Europe. We wanted to contribute to existing efforts in designing genetic monitoring methodology for this noble broadleaved species, through the screening of genotypes with different health status and belonging to two phenological varieties [early (var. praecox) vs late (var. tardissima)] using seven oxidative stress parameters (total protein content, total phenolic compounds content, total flavonoids content, DPPH, ABTS, NO radical scavenger activities and Ferric reducing antioxidant power essay - FRAP). Results of this study provided significant biological message, contributing to better understanding of existing biodiversity of pedunculate oak in Serbia. Four out of seven oxidative stress screening tests (total phenolic compounds content, total flavonoids content, RSC NO and FRAP) clearly discriminated late vs early individuals sampled from selected pedunculate oak gene pool. Although presented results did not show significancy in using mentioned parameters to distinct damaged from vital individuals, nevertheless, knowledge gained through discussion and comparison with previous studies contributed to precise determination of biochemical tests which might be used in future efforts of genetic monitoring of this species.

Key words: antioxidative; biodiversity; ecotype; pedunculate oak; stress

    Branislav Trudić  
    Biljana Kiprovski  
    Saša Kostić  
    Srđan Stojnić  
    Marko Kebert  
    Aleksandar Ivezić  
    Andrej Pilipović  
Anamarija Jazbec  UDK 630* 965.3
How the results of state secondary high school final exams influence the average grade and duration of undergraduate study at Faculty of forestry and wood technology, University of Zagreb?      
This study was motivated by a discussion how the results of state maturity influence on academic undergraduate performance (average mark) and the number of year students take to complete their undergraduate studies (study duration). There are three compulsory subjects on the state maturity: Mathematics (MATH), Croatian (CRO) and foreign (FORL) language. MATH and CRO can be deployed on two levels. Were analysed data using data from a questionnaire among 257 graduates from 2016 to 2018.(Table 1) A multivariate linear regression was used to analyse if and how marks of subjects from state maturity predict undergraduate study achievement: average mark and duration of study with logarithmic transformation. In order to consolidate these results, we used canonical correlation as a variation on the concept of multivariate regression and correlation analysis. analyse the relationship between two sets of variables, maturity marks: MATH, CRO and FORL and undergraduate performance: duration and average mark of study. Mark of MATH on maturity is statistically significant predictor of average mark and duration of undergraduate study (Table 4). The higher MATH the higher average grade of the study and the shorter duration of the study. Results of canonical correlation shows that only the first canonical correlation rc1=0.3576 is statistically significant F(6,392)=5.43, p<0.001. The first canonical variate for undergraduate performance shows most weight on average mark than duration of study.

Key words: forestry students; wood technology students; state maturity; undergraduate study performance; multivariate regression; canonical correlation

    Anamarija Jazbec  
Mirjana Ćuk, Radenko Ponjarac, Dušan Igić, Miloš Ilić, Marius Oldja, Dragana Vukov, Andraž Čarni  UDK 630* 233+187
Historical overview of the Deliblato sands afforestation      
Deliblato Sands is one of the largest sandy areas in Europe. Given that developing of vegetation on the sand is a slow process, followed by human activities that devastate the plant cover (grazing, deforestation), the free-moving sand on Deliblato Sands exited until the 18th century. Unbound sand hindered the development of agriculture in the entire southern Banat region, so it was necessary to start a more intensive process of restraining sand masses. The afforestation of this area began in 1818 and is still ongoing. In the process of afforestation, nine periods can be recognized that differ in relation to afforestation/reforestation techniques, the choice of species or the organizational structure of the forestry units (and countries) of the area of Deliblato Sands belonged throughout history.
The most significant results in the binding of free moving sand were achieved by the application of black locust (Robinia pseudoacacia L.) seedlings with juniper scrub (Juniperus communis L.) laid down on open sandy areas and sowing different species of grass between the rows of seedlings. This technique has been applied since the IV afforestation period (1878-1898). The largest areas were afforested in the V period (1898-1918), when parts of Deliblato Sands were formally protected for the first time in history as areas of importance for the preservation of biodiversity. The species most used in afforestation are black locust (Robinia pseudoacacia L.), Scots pine and black pine (Pinus sylvestris L., Pinus nigra J. F. Arnold), poplars (Populus sp.), and some shrubby (e.g. Juniperus virginiana L.) and herbaceous species (e. g. Ammophilla arenaria (L.) Link, Festuca vaginata Willd., Leymus arenarius (L.) Hochst., Carex arenaria L.). Today, Robinia pseudoacacia L. is most common tree species on Deliblato Sands and it occupies almost a third of the entire area.

Key words: stabilization of sand; vegetation on sand; continental sand dunes; black locust

    Mirjana Ćuk  
    Radenko Ponjarac  
    Dušan Igić  
    Miloš Ilić  
    Marius Oldja  
    Dragana Vukov  
    Andraž Čarni