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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   233
There are at least two indicators that are needed in order to develop and improve the condition of any economic activity: the current condition as a starting point, and the goal to be achieved. It goes without saying that all the principles of the profession should be strictly followed. This is called Strategy or Forest Policy in forestry, which, as we have already mentioned in an earlier column, is sadly missing (not counting the 2003 policy set forth by the Government). Still, the quality, naturalness and biodiversity of Croatian forests have been preserved by strict adherence to the principle of sustainability applied for two and a half centuries. This renewable natural resource makes a certain amount of profit by providing wood products, raw material for wood-technological processing and non-market forest functions. Not only is this modest fi nancial profit used to cover investments in this economic branch, but a certain amount is also paid into the state budget. Why do we say "modest profit"? On the one hand, forest wood products do not have their market value, yet on the other, it is required that they make profi t. Profit can be made if the principles of sustainable management are neglected, e.g. savings are made by postponing or even eliminating silvicultural activities from the Management Plan, increasing the annual cut and carrying out "qualitative felling" (figuratively: veneer producers advance, the others halt!). Is it possible that we have reached, or will soon reach this situation if we keep silent and not raise our voice against the current state of aff air? Th e current state of affair primarily involves non-market evaluation of wood assortments and drastic cuts in the financial means intended for the preservation of non-market forest values. Th ese means should, according to the law, be paid by all the users. Th e goals and terms of completion of silvicultural activities are prescribed by the Management Plan. In terms of wood assortments, it is necessary to identify future bearers of production in the stands. In order to obtain the best quality assortments, the bearers should be favoured through management and protection activities. For example, in the case of oak, these activities may last until a stand reaches 160 years of age, or in other words, for four generations of forestry experts. We may well ask ourselves if this is at all worthwhile if such a high quality wood product does not achieve an adequate price on the market. If wood processing companies were forced to pay a proper price, then an oak veneer log would end up under the veneer knife (cut to 0.8 mm thickness) and not in a sawmill cut into unedged boards or even worse, into planks, which a foreign wood processor would then "upgrade" into veneer.
In a matter of fact, there are still many who do not realize that such an uneconomic attitude towards forest wood assortments squanders the country´s national resources. Sadly, it is the State (politics) as the major owner of this resource, that supports this attitude by favouring private capital and by falling for the incessant complaints of wood processing companies about excessive prices of wood assortments (which are cheaper by half that those on the European market and the lowest in the nearest environment). "The same old tune" was played at a recently held conference of wood processing companies in Opatija; at the same time, the competent foresters, as usual, did not say a word. Th ere was nobody to raise any questions, such as, for example: why does the announced minimal increase in price relates only to forest products an not to other production costs when wood as the basic resource participates in the highly finalized product with about 14 to maximally 20% of the product value? Or: how come that it is profitable to produce pellets from raw material and not from the already dry biomass resulting from final wood processing? In the rest of the world, where the price of forest products is realistic, pellets are normally produced from waste biomass.
There is a term in economics known to many – "position rent". It is precisely this rent that our wood processing companies possess – to some of them, logs, conditionally said, fall straight to the depot – how come they are not more competitive than those who have high transportation costs? The production of a high quality wood product that has high additional value (which leads to higher employment) and is competitive on the world market requires knowledge, expertise, worker skills and technologically equipped producers. How much is invested in knowledge, expertise and new wood processing technologies? Or maybe, in the race for easy and short-term profit, companies invest money outside the basic activity (e.g. housing), while at the same time remaining in debt to the suppliers and requiring prolongation of payment or even write offs of debts for wood as the basic raw material. In principle, private entrepreneurs say that salaries in the real sector are lower than salaries in the public sector. According to the available data, this is true, but whether these are real salaries or only "reported" salaries so as to pay lower taxes and levies is doubtful.
The means invested in non-market forest functions help obtain FSC certification for Croatian forests. These are used exclusively by wood processing companies which sell their products by stressing that their raw material comes from certifi ed forests. Why then do they support the reduction and even elimination of these means? Are contracts on the delivery of certain quantities of wood raw material mutually honoured, or are more raw materials required from forestry only at the time of favourable market rise, but when the conditions worsen then not even the contracted quantities are accepted?
There are many more issues to discuss, but we mentioned the few above in order to provide the authority with food for thought. There is one more vital question: are wood processing companies sawing off the branch they are sitting on? Naturally, these questions do not refer to an, unfortunately, small number of correct wood processing companies, but to the majority of those who have sauntered in wood processing waters, seeking easy profit regardless of the consequences for the forests. Th ey look for the justification for their incompetence and ignorance everywhere else but at their own doorstep.

Editorial Board

Davorin Kajba, Ivan Andrić  UDK 630* 165 (001) 235
Estimation of genetic gain, productivity and phenotypic stability of poplar clones in the area of eastern Croatia      
Summary:Research into phenotypic stability, adaptability and productivity of poplar clones at younger plantation was conducted in the lower course of the River Drava and the tributary of the River Danube in the eastern Croatia. In this area, the construction of river infrastructure has led to severe changes in the water regime. It is for this reason that the selected poplar clones should be adapted to the specific new condition of low groundwater levels. The assessment of genetic parameters, productivity and phenotypic stability for 14 poplar clones at plantation age of 2+5 years were evaluated in five clonal trials in the area of Eastern Croatia. The tests were set up at planting distances of 6 × 6 m randomized with 16 plants per block and four repetitions. At the moment of experimental plot establishment, the planting material was 1/2 and 2/3 years old. Statistically significant interclonal variability in production and survival was found in particular clonal tests. Mean survival in the clonal test established with plants aged 1/2 years was 72 % on average, whereas it was 95 % in the test with plants aged 2/3 years, which suggests that using of planting material at age 2/3 years is much more successful. Research on adaptability and genotype × environment interaction were conducted for the same eight poplar clones in three trials. From a silvicultural standpoint, the most suitable clones for generating optimal modifications, as a rule, were those of high phenotypic instability. Their cultivation is justified on optimal sites, as well as on less favourable sites when are provided agrotechnical measures and applied adequate protection measures. Based on the size of regression coefficients and regression analysis, it can be concluded that the tested clones can be divided, in terms of phenotypic stability and productivity, into three groups: a) phenotypically stable clones of medium productivity and a tendency to adapt to all environments (´I-214´, ´M 1´, ´S 6-36´, ´S 6-20´; b) moderately stable clones, of moderate productivity which manifest a tendency to adapt to all environments (‘710’, ´Bl Constanzo´, ´Pannonia´); and c) phenotypically very instable clones of high production capacity, with specific adaptation to optimal sites (´S 1-8´). Levels of the genetic control for the growing stock, heritability values (h2) and genetic gain (∆G) were assessed on the basis of selecting five or one of the best clones. The expected genetic gain was compared with the obtained experimental data. Assessment of the heritability values (h2) ranged from 0.40 to 0.90, which indicates that the traits of production and adaptability is under a high degree of genetic control. The obtained genetic gain (∆G) in growing stock production for the best five selected clones was somewhat higher than expected and ranged from 15.30 to 45.12 %, whereas it was between 30.88 and 81.03 % for one best selected clone. In order to minimize the risk of cultivating one clone (monoclonal culture) and increase plantations stability, we will favour the cultivation of a mixture of five clones of divergent genetic constitution. The results of this research confirm that even at such a young plantation age the quality of a particular habitat has conditioned modifications in average clone values of growing stock and survival. They also indicate the amount of production to be expected from the mixture of these clones or from the cultivation of a particular clone.

Key words: adaptability; genetic parameters; genotype × environment interaction; poplar clones

    KAJBA, Davorin      ŠL
    Andrić, Ivan  
Aleksandar Mešić, Tihomir Miličević, Dinka Grubišić, Boris Duralija, Ante Marić, Anamarija Popović  UDK 630*453
(Cameraria ohridella) (001)
Foliar treatments against horse chestnut leaf miner (Cameraria ohridella)      
Summary: Horse chestnut leaf miner (Cameraria ohridella) is the most important pest of horse chestnut (Aesculus hippocastanum), common tree in European parks. The pest regularly develops high populations of larvae which damage leaves. It could be controlled with foliar spraying or with trunk injections of insecticides (endotherapeutical method).
The paper presents results of in-city trials with foliar treatments against horse chestnut leaf miner’s larvae. Knapsack mist-blower was used for insecticides application (dates of applications are presented in Table 2) on trees higher than 15 m. Insect growth regulators (IGRs), imidaclopride, spinosad and Bacillus thuringiensis (Table 1) were applied with liquid rate of 3 l per one tree.
Each year, leaves were examined five times; each time 400 leaves were examined for each trial variant and numbers of mines per leaf were counted and statistically analyzed.
The best results were achieved after two applications in one season (with average period between two applications of 43 days) with imidaclopride (91.4–97.2 % efficacy) and insect growth regulators (IGRs) – diflubenzuron (89.5–94.9%), hexaflumuron (84.6–96.3 %), methoxyfenozyde (85.6–94.9 %) and lufenurone (85.8–94.4 %). Single application of imidaclopride (88.9–97.7%) and diflubenzuron (85.9–95.3 %) did not achieved statistically different efficacy in horse chestnut leafminer control than two applications in one season. Efficacy of spinosad (67.4–89.3%) and combination of B. thuringiensis and imidaclopride (52.4–91.6 %) did not satisfy. Even lower efficacy was achieved after two applications of B. thuringiensis in one season (52.2–83.7 %) and after single application in one season (30.3–84.7 %) (Table 8). In this period untreated control trees were infected with average of 22.4 –84.2 larvae/leaf (Tables 3–7), depending on date of examination.
Results of those five-year trials results show that is possible to protect horse chestnuts if foliar insecticides application is provided in period of first generation’s larvae hatching. The most suitable insecticides were insect growth regulators (IGRs), while imidaclopride is not appropriate in urban area due to its high toxicity. B. thuringiensis provides very good initial protection, but it has very poor residual effect so it is advisable to apply B thuringiensis twice or more times in one season (Tables 3–8).

Key words: Bacillus thuringiensis; efficacy; foliar threatment; horse chestnut protection; IGRs; imidaclopride; insect growth regulators; spinosad

    Mešić, Aleksandar    
    Miličević, Tihomir    
    Grubišić, Dinka    
    Duralija, Boris    
    Marić, Ante    
    Popović, Anamarija    
Ljiljana Šestan  UDK 630*181.1 + 111
(Quercus pubescens Willd.) (001)
Simulation model of the effect of air temperature on the leaves phenophases of the pubescent oak on the island of Pag      
Summary:The impact of climate change has been observed in case of occurrence and duration of seasons which in deciduous forest manifest through changing of the leaves. Monitoring changes in the development of leaves was carried out through phenological observations, where specific change corresponds to a particular phenophase. In researching this issue, despite numerous studies, phenophases have not been studied as a system, but individually and then compared (e.g. Ahas et al., 2002; Menzel, 2000). Most previous studies of this issue were related to classical statistical methods, such as descriptive statistics, linear regression, correlation, multiple regression (e.g. Ahas et al., 2002; Chmielewski and Rőtzer, 2001; Menzel, 2000). The most commonly used method, the method of linear regression, assumes a linear relationship between phenomena. However, as relations between elements of complex natural system are not always linear, the application of the linear regression method is not sufficient for the development of a model of the entire process, without losing specific components and including the environmental influence (Šestan 2010). Therefore, in this study, to model and study the effect of air temperature on the system of phenophases, the system-dynamic principle was applied.
The research of the impact of the most important climatic factor – air temperature, on the phenophases, was conducted on experimental plot in the pubescent oak forest (Quercus pubescens) on the island of Pag (Adriatic Sea). Systematic phenological observations were carried out there during period 1993–2005. Six phenophases marked as F0, F1...F5, were distinguished:
1. Dormant vegetation, all the leaves have fallen (F0),
2. Leaves begin to develop (F1),
3. Leaves are fully developed (F2),
4. Leaves begin to change colour (F3),
5. Leaves have completely changed colour (F4),
6. The leaves begin to fall (F5).
The relevant indicators of the dynamics of phenophases were obtained by collecting and organizing data through phenological observations: average time of appearance in the annual cycle, the average duration of the annual cycle and the frequency of certain phenophases (table 1). Based on systematic observations of phenological data, the frequency of crossing between phenophases was determined as the neighbouring phenophases state differences (table 2). Data on the dynamics of air temperature were obtained from the State Meteorological and Hydrological Institute. The process of determining the characteristic distribution was carried out for the weekly mean air temperature for all phenophases when they are present, or when the state of phenophase is greater than 0 (table 5).
Gathered and processed data have allowed the building of the simulation model of the system of phenophases. Simulation model was based on system-dynamic approach (figure 1). In order to determine whether the model represents the real system satisfactorily, the process of model validation was carried out (table 6 and table 7).
The research of the influence of air temperature on leaf phenophases was conducted with the developed model, through different scenarios from 1 to 6. The results of the simulated scenarios (table 8, 9 and 10) confirmed the crucial influence of temperature on the leaves phenophases. The results of these studies have shown that on average, phenophases F1, F4 and F0, are the most sensitive on the fluctuations in air temperature, but above all F1 as first that reacts to change. However, they also showed that all phenophases are not equally responsive to temperature changes. It is interesting that phenophases F3 and F5 showed the least sensitivity to temperature changes, in terms of average time of occurrence. Such result of the simulation experiments indicates that those phenophases are significantly influenced by other factors.

Key words: climate changes; modelling; phenology; phenophases; pubescent oak; simulation; system-dynamic approach

    Šestan, Ljiljana    
Marjana Westergren, Kristjan Jarni, Robert Brus, Hojka Kraigher  UDK 630*165
(Fraxinus excelsior L.) (001)
Implications for the use of forest reproductive material of common ash (Fraxinus excelsior L .) in Slovenia based on the analysis of nuclear microsatellites      
Summary: Assumption that forest reproductive material is better adapted to local conditions is the basis of current forest policy that promotes the use of local material. Genetic diversity and structure of two approved seed stands and three non-approved stands of Fraxinus excelsior L. were analysed with nuclear microsatellites to get genetically based support for the use of its reproductive material in Slovenia. Genetic diversity was high (HE = 0.80) and differentiation between populations measured as FST (FST = 0.018) low to nonexistent when measured with genetic distances. Calculated allelic indices for seed stands were the same or a bit above the Slovenian average with two exceptions. Based on the analysis of five microsatellite loci, no restrictions for transferring forest reproductive material within the studied range can be presented. However, collection of forest reproductive material from seed stand Rodik should follow good seed collection practices to ensure high genetic diversity of reproductive material.

Key words: common ash; forest reproductive material; Fraxinus excelsior; genetic diversity; genetic structure; microsatellites; Slovenia

    Westergren, Marjana    
    Jarni, Kristjan    
    Brus, Robert    
    Kraigher, Hojka    
Andrej Pilipović, Saša Orlović, Nataša Nikolić, Milan Borišev, Borivoj Krstić, Srđan Rončević  UDK 630*561 +161 (001) 273
Growth and plant physiological parameters as markers for selection of poplar clones for crude oil phytoremediation      
Summary: Phytoremediation is an emerging technology where plants are used for environmental cleanup. Crude oil contaminated soils are one of the most challenging tasks for phytoremediation applications due to the complexity of the process affected by variability in chemical composition of oil, plant-microorganism interactions and phytotoxicity of contaminants. Although signs of phytotoxicity are very often easily visible, sometimes plant physiological processes can indicate stress in plants due to the presence of xenobiotics in cases without visible signs. This paper presents investigation of the potential of various poplar (Populus sp.) clones for phytoremediation of soils contaminated with crude oil through assessment of physiological parameters. Biomass production together with: (i) nitrate reductase activity; (ii) net photosynthesis/dark respiration, (iii) proline content (iv) chlorophyll fluorescence and (v) pigments contents were studied. Investiagted clones showed various reactions to the different levels of soil contamination.

Key words: crude oil contamination; physiological parameters; phytoremediation; poplars

    Pilipović, Andrej    
    Orlović, Saša  
    Nikolić, Nataša  
    Borišev, Milan  
    Krstić, Borivoj  
    Rončević, Srđan  
Vlado Goglia, Josef Suchomel, Josip Žgela, Ivan Đukić  UDK 630*304 + 964 283
Forestry workers’ expossure to vibration in the context of Directive 2002/44/EC      
Abstract: Continuous efforts are being made to limit the harmful vibration transmitted from grip handles and stearing wheels of forest machinery to operators´ palms and fingers, known as hand-arm vibration. Among these efforts the ´´Directive 2002/44/EC´´ definitly holds an outstanding position. The document describes clearly the procedure for determining the level of the hand-arm as well as the whole-body vibration exposure and follows all the requests defined by the International Standards ISO 5349-1 and 2, i.e. ISO 2631-1, 2 and 3. Special attention has to be paid to the exposure of forestry workers to hand-arm vibration, as occupational deseases caused by them are very frequent among this population. In order to adjust the safety measures at work to European standards, national ´´Regulations on protection of vibration exposure risks at work´´ (NN55/2008) have been issued. Since January 1, 2012 they are being obligatory in agriculture and forestry. The human exposure to vibration is, as is generally known, expressed in a so called energy equivalent A(8) determined by a procedure described in the International Standard ISO 5349-1-2001. The A(8) value depends not only on the vibration magnitude at individual working operations, but also on the exposure duration, i.e. the duration of each individual operation. Of course, the total duration of all working operations during the working day will be the direct consequence of the quotas set and accepted for various groups of forestry operations. Therefore the efforts to limit the worker´s exposure to vibration means exposure time reduction or, in other words, adjustment of the quotas (Goglia et al.2011). So it is necessary to take immediate action and determine the energy equivalent A(8) values according to the existing quotas for all work places with high frequency of occupational deseases. Hereafter, by correcting the quotas vibration exposure times have to be adjusted to the limits set in the Directive 2002/44/EC and the corresponding national Regualtions.

Key words: ergonomics; exposure; limit values; vibration

    GOGLIA, Vlado    ŠL
    Suchomel, Josef  
    ŽGELA, Josip    ŠL
    Đukić, Ivan