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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: Boris Hrašovec

Uredništvo   5
At an elevation of about 3000 m asl, when the air temperature drops between 5 and 10 °C below zero, the snow developed in the clouds begins to fall. Passing through the warm layer between 800 and 2000 m above sea level, the snow melts and becomes rain. In the zone of cold air below 800 m the raindrops cannot revert to snow but continue falling as rain, which immediately freezes upon impact with any cold surface it encounters. In terms of meteorology, this is supercooled rain because the raindrop temperature is below 0 °C (it can also be below – 40 °C), but it freezes the moment it touches the ground.
Such or a similar structure of air masses distributed across the elevations at which freezing rain develops, was formed within the Mediterranean Cyclone Ilija, which affected the weather in Croatia on Sunday, February 2nd, 2014, when a large part of Gorski Kotar was hit by freezing rain, causing havoc on state-owned and private holdings, in the nature and on the infrastructure. Forests, orchards and power transmission lines were heavily affected, the roads were glazed with ice, and the roads were partially or completely blocked for several days by fallen trees and ice-burdened branches leaning over the roads. About 80 % of the population (14,000 households) were left without electricity. The County Prefect proclaimed a state of natural disaster for the entire region. Rescue teams (forestry employees and forestry infrastructure, fire fighters, builders and others) that came to the area managed to restore the semblance of normal life over the next 10 days. It will take months and even years to remediate the damage incurred by the freezing rain and snow. Damage suffered by social and private subjects in the region is currently being assessed and submitted.
In this report we will primarily focus on the damage incurred on and in the forests. Some time ago, the company "Hrvatske Šume Ltd", the Risnjak National Park and the Faculty of Forestry assessed the damage in the region under their management and are currently drawing up restoration programmes. Damage assessment was submitted, among others, to the Primorje-Gorski Kotar County, which will add it to the rest of the damage assessments, develop a restoration programme and apply to the EU Fund for help. According to the assessment made by the company "Hrvatske Šume Ltd", damage was incurred over 43,025 ha of state forests (including the Risnjak National Park) and 9,723 ha of private forests. The amount of damaged wood mass encompasses 2,494,651 m3 of technical wood (2,183,154 m3 in state forests + 311,497 m3 in private forests) and fuelwood 1,774,426 m3 (1,256,537 + 517,889). Excluding the Risnjak National Park which covers an area of 39,172 ha (29,449 + 9,723), as much as 1,517,544 m3 of technical wood and fuelwood (1,035,735 + 418,809) were damaged in the value of 285.185 million kn (214.312 + 70.813). The exploitable wood mass of technical wood and fuelwood was estimated at 750,234 m3 (483,175 + 267,059 m3), reaching 138.470
mil. kn (98.214 + 40.256 kn), which means that the damage rose to 146.655 mil. kn (116.097+ 30.558 kn). Damage on forest roads was assessed at 3.389 mil. kn, on forest tracks at 9.115 mil. kn, and work on public roads at 0.468 mil. kn. Damage in the National Park was assessed at 24.084 mil. kn., and the at the Faculty of Forestry facilities at 0.131 mil. kn. Naturally, cost of remediation should be added to these claims. Broadleaves were the most heavily affected. The percentage of destroyed wood mass ranges from 60 % in the forest offices of Rijeka, 48 % in Crni Lug, 43 % in Gerovo, 38 % in Fužine, 34 % in Tršće, 34 % in Prezid, 23 % in Lokve, 23 % in Delnice, 6 % in Mrkopalj, and 2% in Skrad to none in the forest offices of Ravna Gora, Vrbovsko and Gomirje. The average damage for the Delnice Forest Administration is 30 %.
In view of these facts, all those responsible for the management and care for the forests in the afflicted areas are faced with an enormous professional challenge of damage restoration. We firmly believe that they are capable of responding to this challenge.
Editorial Board

Igor Poljak, Marilena Idžojtić, Irena Šapić, Joso Vukelić, Marko Zebec  UDK 630*164 (001) 7
White and black alder are our indigenous noble broad-leaved species. In Croatian forestry, black alder has an important place, while the white alder does not have economic importance and it is becoming increasingly neglected. White alder appears on shingle, active material in mainstream, on river banks and terraces which are periodically or at least sporadically flooded. It very rarely occurs on its own on drifts and it does not appear in swamp habitats which are characteristics of black alder. The farther the area is from the mainstream watercourse, the higher is the probability of black alder supervention. Finally, in swampy, peaty areas, black alder forms its stands.
Stands of white and black alder are relatively clearly distinguished in the researched area, although somewhere is common their joint supervention on the same stands. In the areas where white and black alder habitats are overlapped, their spontaneous hybridisation is possible. White and black alder crosses have been so far noticed only in NW Croatia.
Variability of a species is one of the most important preconditions for its adaptive potential in variable environment conditions, and in a long term, for survival of the species. That is, variability insures adaptability of populations towards environment changes through generations. The optimal variability of white and black alder in the area of riparian forest ecosystems is disturbed by negative anthropogenic activities.
This paper researches the intra-population and inter-population variability of white and black alder in five natural populations along rivers Drava and Mura on the basis of morphological leaf traits.
Material for the morphometric analysis was collected in five natural populations in the areas of Podravina and Međimurje, along rivers Drava and Mura (Figure 1). Three populations of white alder and two populations of black alder were included in the research. Each population was represented by 20 trees and each tree by 20 healthy and undamaged leaves, collected from short fertile shoots of the outer, light-exposed part of tree top. The leaves were scanned and measured by the WinFolia programme. Ten foliar traits were defined and measured altogether (Figure 2). From the measured traits, the following ratios were derived: MPW/BL, PW1/BL, PMPW/BL, PL/BL.
The measured morphological traits were shown through descriptive statistical parameters. For determining the intra-population and inter-population variability, the univariate analysis of variance was used. For determining similarities or differences of analyzed populations on the basis of measured morphological leaf traits, multivariate statistical methods were used – cluster and discriminant analysis. These statistical analyses were conducted using the statistical programme STATISTICA 8.0.
The results of the descriptive statistical analysis are presented in Table 1, by population. For both species, the trees within populations differ significantly on all analysed traits (Tables 2 and 3). Populations of white alder do not differ significantly between themselves on any trait, while the differentiation of populations of black alder is at significant level 0,01 inherent for variables BL, PMPW, LA1 and LA2. For each species individually, smaller variability among populations has been determined, while the remaining component regarding variability of the leaves within the tree takes up the largest proportion of the total variance (Tables 4 and 5).
It can be seen from the dendrogram that the inter-population variability of black alder is greater than the inter-population variability of white alder (Figure 3).
In order to determine which traits best discriminate researched populations and to additionally clarify the trend of their differentiation, discriminant analysis was conducted (Tables 6 and 7, Figure 4). For the populations of white alder, it was determined that canonical projections of trees within populations are weakly connected, in the sense that the populations are almost completely overlapping. The weak differentiation between populations and great variability within populations can be explained by similar ecological conditions of their supervention and by intensive flow of genes between populations. Although the canonical value projections for individual trees are partly overlapping, the trend of differentiation between populations of black alder is clearly perceived. Considering that the researched species belong to different river and forest systems, we can assume that the obtained differences in variability are caused by hydrological and ecological influences.
Although the trees of white and black alder clearly differ between themselves, it can be seen that individual trees from white alder population Varaždinsko jezero cross to the right side of the diagram (Figure 4). Considering that the mentioned trees are intermediary in relation to researched species, we can conclude that it is the case of hybrid individuals. Through subsequent analysis, intermediary traits on most researched variables were identified for the crosses (Table 8).
Genetic diversity is one of the basic preconditions for adaptability of a certain species to particular habitat conditions. Through this research, the knowledge of the intra-population and inter-population variability of white and black alder on Podravina – Međimurje area was gained. This knowledge represents the basis for further research that needs to be conducted in order to obtain guidelines for improvement and preservation of genetic resources of the alder species in Croatia.

Key words: white alder; black alder; variability of leaves; hybrids; Mura; Drava

    Poljak, Igor  
    IDŽOJTIĆ, Marilena      ŠL
    Šapić, Irena  
    VUKELIĆ, Joso      ŠL
    ZEBEC, Marko    ŠL
Jaroslav Holuša, Emanuel Kula, Filip Wewiora, Karolina Lukášová  UDK 630*453 (001) 19
The increasing threat to forests from the gradual increase in Ips cembrae abundance necessitates more precise information concerning its ecology, monitoring, and control.
Cembräwit® pheromone traps and trap trees were used to evaluate I. cembrae flight activity and infestations, respectively, during outbreaks in 2007–2009 in the Czech Republic. Emergence of the next generation was also evaluated from trap logs and forest litter.
Flight activity was detected from late April to early July and lacked clear peaks. Trap trees were invaded evenly along the entire profile of the trunk. Parent galleries were longer and numbers of larval galleries were fewer in the upper parts than in the lower parts of trap tree trunks. Gradual fly-out of beetles from infested larch wood under laboratory conditions during winter confirmed that adults, larvae, and pupae of the offspring generation overwinter in such wood. The trapping of beetles emerging from litter confirmed that I. cembrae also overwinters in the litter near the trees where development was completed.

Key words: Ips cembrae; pheromone-baited trap; trap tree; flight activity; dispersion; overwintering

    Holuša, Jaroslav  
    Kula, Emanuel  
    Wewiora, Filip  
    Lukášová, Karolina  
Bojan GAVRILOVIĆ, Branka GAVRILOVIĆ, Srećko ĆURČIĆ, Dejan STOJANOVIĆ, Dragiša SAVIĆ  UDK 630*453 (001) 29
Leaf beetles (Coleoptera: Chrysomelidae) have not been sufficiently studied in Serbia so far. The species of the family were investigated in a protected area – the Fruška Gora National Park (Vojvodina Province, Northern Serbia) over the period of 11 years (2001–2011). Mt. Fruška Gora is an isolated island mountain in the Pannonian Plain and is characterized by a complex assembly of forest, meadow, shrubby, grassland, cultivated land, wetland, and aquatic phytocenoses. At total of 99 chrysomelid species from 42 genera and 11 subfamilies were identified from the area. The data on nutritional preference of the found Chrysomelidae species and host plants are given by own observations in nature. Furthermore, economically important leaf beetle species (i.e., forest and crop pests) are identified and briefly discussed as well. The registered species can be classified into seven chorotypes of Holarctic and three chorotypes of Europe according to zoogeographical analysis.

Key words: Chrysomelidae; Serbia; diversity; trophic associations; distribution

    GAVRILOVIĆ, Bojan  
    GAVRILOVIĆ, Branka  
    ĆURČIĆ, Srećko  
    STOJANOVIĆ, Dejan  
    SAVIĆ, Dragiša  
Ante P. B. KRPAN, Željko TOMAŠIĆ, Igor STANKIĆ  UDK 630* 537 + 562 (001) 43
The paper shows the results of the third year of research into biopotential and energy properties of indigobush. The research is planned to last for 6 years. According to the annual plan, the experiments were done in sample plots 1 and 3 in the third year of research. A research block polygon was established in a thirteen-year-old natural stand of indigobush in the compartment 126a of the Management Unit Posavske Šume, Sunja Forest Office, Sisak Forest Administration. The research is based on a project protocol and annual work plans and is carried out in four experimental fields, each containing six 5 x 5 m experimental plots. The basic task of the scientific-research project is to determine trends in bioproductive or bioenergy capacity in naturally planted indigobush at repeated felling operations. The time rhythm of the research was determined by the number of the plot, in combination with the project protocol and annual work plan.
Indigobush, particularly in the lowland systems of the Posavina region, covers large areas of forest soil. In some of these areas indigobush is so widespread that its shade prevents natural regeneration of stands of valuable autochthonous tree species. As a species of light, indigobush invades forest areas after tree cutting and overshadows the desired autochthonous young growth with its dense canopy. For this reason, it is perceived as an aggressive plant and a very dangerous weed, since not only does it considerably hinder the regeneration of Croatia’s most valuable lowland forests but also makes it more costly.
The possibility of using indigobush biomass for energy is limited by a number of factors. The most important ones include the quantity of biomass per surface unit and the profitability of its harvesting, chipping, transport
to the user, storage and drying to the desired level of moisture. The energy value of indigobush wood has been firmly confirmed by various literary sources. Extensive research into bioenergy potentials of different plant species, including indigobush, has been conducted in Hungary. According to Marosvölgyi et al. (2009), experiments related to naturally grown indigobush and energy plants showed that indigobush is an exceptionally suitable material for energy production. Initial moisture of one-year-old sprouts during one-month storage dropped from 47.0 % to 34.2 %. The measured fuel value at W = 34.2 % was 12.7 MJ/kg. In dry condition, the energy value of indigobush is 20.2 MJ/kg. In comparison, dry pine sawdust has a slightly lower value of 19.7 MJ/kg. Moreover, the ash content in indigobush was found to be 1.5 %, while the content of volatile materials was relatively higher. Puljak (2005) burned indigobush in a biomass energy plant in Ogulin to confirm its energy value as fuel by monitoring the temperature of the firebox, smoke gases and water, which satisfied the set criteria.
Figures 2 and 3 show the data for plots 1. A spatial arrangement of the stumps, their form and surface size are shown in the layout. There are from 12 to 20 stumps in the plots. The number of the stumps is not an indicator of indigobush productivity (the case with a plot in field IV with the lowest number of stumps and field 1 with the highest). As seen from table data, indigobush productivity correlates with the number of the sprouts and their dimensions. The number of the sprouts in the plots varies from 278 pcs/plot (111,200 pcs/ha) to 389 pcs/plot (155,000 pcs/ha). The mean heights in the plots range from 2.23 m to 2.48 m and the mean diameters vary from 7.35 mm to 8.58 mm. The lowest sprout mass of 11,000 kg/ha was recorded in sample field IV, and the highest of 18,400 kg/ha was found in field III. The mean value of green biomass bioproduction during one vegetation season amounts to 14,776 kg/ha of green indigobush mass per hectare.
Sample plots 3 were measured for the first time. The results of measurements are given in Figures 4 and 5. The number of the stumps ranged from 13 to 21, and that of the sprouts from 254 pcs/plot to 292 pcs/plot, or from 101,600 pcs/ha to 116,800 pcs/ha. The mean heights in the plots were from 2.69 m to 2.88 m, and the mean diameters were from 10.60 mm to 12.43 mm. The sprout mass ranged from 61.50 kg/plot or 24,600 kg/ha to 89.30 kg/plot or 35,720 kg/ha. The average overall green mass production in plots 3 amounts to 30,700 kg/ha, and the average annual production amounts to 10,233 kg/ha.
Variance analysis was used for indigobush breast diameters and sprout heights in plots 1 and 3. The results are given in Table 1 and 2, and mean values are presented graphically in Figures 6, 7, 8 and 9. It can be concluded from Table 1 and variance analysis that there is a statistically significant difference in mean breast diameters between the analysed sample fields (F = 9.597; df = 3; p < 0.001). The Tukey post hoc test showed a statistically significant difference between field III and fields I and IV, as well as between field I and field II and III. The statistically significant highest breast diameter of 8.58 mm was found in sample field III.
Variance analysis found a statistically significant difference in the average height values for the analysed sample fields (F = 17.38; df = 3; p < 0.001). The Tukey post hoc test showed that sample fields I and IV differed statistically significantly from fields II and III, whereas the former (I and IV) and (II and III) did not differ from one another.
According to the Tukey post hoc test, there was a statistically significant difference among the average values of breast diameters in the three-year-old stand (Table 2) between experimental fields 1 and 4, as well as between 2 and 4. The mentioned average values between exp. fields 3 and 4 did not show any statistically significant difference.
Related to the analysis of the average height values, a statistically significant difference was also found between the sample fields (F = 10.39; df = 3; p < 0.0001). According to the results of the Tukey post hoc test, the average height valuein sample field IV was found to differ statistically significantly from the average values in all other sample fields. These values did not differ statistically significantly in sample fields I, II and III.
Table 3 shows data of indigobush bioproduction analysis, both green and dry mass, in plots 1 and 3 in the sample fields, as well as data calculated per surface hectare. Data are also given of the percentage share of moisture calculated on the basis of laboratory research into indigobush wood samples and dry matter, expressed as a difference between the percent share of moisture and 100 % amount. The moisture content of indigobush wood at the moment of harvesting is important in terms of price, which depends on water content and a possible need to dry the chips in the storehouse until they reach the optimal water content. In exp. plots 1 the indigobush wood moisture percentage ranges from 32.78 % to 34.50 % (33.71 % on average), meaning that all percentages are lower than 35 %. Exp. plots 3 contain even lower values, which oscillate from 30.09 % to 31.90 (31.33 % on average). Dry wood matter in plots 1 ranges from 18.21 kg to 30.46 kg, with the mean value of 24.47 kg, and in plots 3 from 41.88 kg to 60.97 kg, with the mean value of 52.77 kg. Dry wood matter in plots 1 is from 7.28 t/ha to 12.18 t/ha, with the mean value of 9.79 t/ha, and in plots 3 from 16.75 t/ha to 24.38 t/ha with the mean value of 21.09 t/ha.
In plots 1, which are harvested every year at the end of vegetation, bioproductivity was found to vary. After the first vegetation in 2008, dry matter amounted to 12 t/ha (Krpan and Tomašić 2009), after the second (2009) it came to 7.87 t/ha (Krpan et al. 2011a,b), and after the third (2010) it was 9.79 t/ha. It can therefore be concluded that, in relation to the first vegetation, bioproduction manifests a downward trend. The average annual production of two-year-old indigobush is 8.19 t/ha, while that of three-year-old indigobush is 7.03 t/ha. Hence, a downward trend in bioproduction is present here as well.
A quantity of 2.68 kg seed or 1,073 kg/ha was collected in exp. plots 3. This result is tentative because a large amount of seed naturally falls off by the time of collection, as well as during collection due to shaking caused by bending the branches. According to our estimates, seed loss may amount to over 50 %. To avoid the possibility of incorrect evaluation, seed loss will not be analysed in more detail here. It is evident from the above that almost all the seed is lost during harvesting after vegetation, handling, chipping and transport and that it cannot be expected to accompany the leaves in the combustion process in energy plants.
The results of indigobush research in the third year of the project show that, despite the established downward trends in bioproductivity, the plant still retains its competitiveness in the field of renewable energy sources, particularly because it occurs and develops naturally. It does not require any agrotechnical measures, nor does it incur any costs (except for harvesting and handling costs), which are otherwise indispensable when establishing and managing energy cultures and short rotation orchards of well-known fast growing tree species.

Key words: indigobush bioproductivity; energy benefit; lowland forest ecosystems; Croatia

    KRPAN, Ante P. B.    ŠL
    TOMAŠIĆ, Željko    ŠL
    STANKIĆ, Igor      ŠL
Marko Zebec, Marilena Idžojtić, Igor Poljak, Maja Zebec  UDK 630*272 55
The park surrounding the Faculty of Forestry and the Faculty of Agriculture, University of Zagreb, is located within the Maksimir Public Garden, east of the Bliznec Brook. Established in the 1950s, and covering an area of 5.7 ha, the park abounds in woody plant species, varieties and cultivars, with a total of 112 plant taxa. Out of these, 37 are Gymnosperms, while Angiosperms are represented by 75 taxa (Tables 1 and 2).
The pavilion complexes serving as a teaching venue for the Faculty of Forestry and the Faculty of Agriculture of the University of Zagreb, and for research in the fields of forestry and agriculture, as well as a number of 19th century buildings, all situated inside the park, represent a rich cross-section of architectural development from the first third of the 19th century to the features of contemporary architecture at the start of the 21st century (Figures 1 to 8). They paint in broad strokes the development of architectural styles and thoughts, showing, incorporated in their detail, some interesting and specific features that are related to the history of Zagreb architecture, as well as the particular qualities associated with the expression of individual authors.
At the time of the park development, the tendency was to design a space primarily intended for the education of forestry and agriculture students, neglecting the aesthetic and ornamental function of the plants. There was no prevailing concept in parallel with the planting of the plant material; the emphasis was rather on the greatest possible representation of different taxa within the park. As a consequence, the park does not open towards the visitor with a comprehensive spectrum of morphological characteristics of the planted taxa.
In the beginning, the main element of the space is always an architectural element, whereas the plants were planted only in the conclusive phase, after the construction. As at the time of development of the park surrounding the Faculty of Forestry and the Faculty of Agriculture insufficient consideration was given to the harmony of horticultural and architectural elements, this paper provides concrete solutions for the selection or modification of horticultural elements, with a view to establish the previously non-existent balance of the natural and artificial forms without aggressive interventions in the space, based on a complex analysis of relations between the spatial features of buildings and the representative morphological features of individual plant taxa.

Key words: architectural elements; horticultural elements; comparative analysis; inventarisation of woody plants; the park surrounding the Faculty of Forestry and the Faculty of Agriculture

    ZEBEC, Marko    ŠL
    IDŽOJTIĆ, Marilena      ŠL
    Poljak, Igor  
    Zebec, Maja