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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

Boris Vrbek  
It is well known that forests are the most valuable renewable natural resource anda common goodof exceptional interest for the Republic of Croatia.
Nature is uniquein terms of its diversity, resourcesand beauty,which is particularlyprominent in Croatia as it owes its exceptional geographic and biological diversity to the intense interweavingof Mediterranean, sub-Alpine, DinaricandPannonian bio-geographiceffects within a relatively small area. Sustainable management and preservation of the natural structure and biodiversity of forests, as well as the permanent maintenance of stability and quality of economic and generally beneficial forest functions are the key principles of Croatia’s forestry.
While human activity has significantly affected the natural composition of forests in the majority of countries, this is not the
case with Croatia - here it has been almost completely preserved,owing precisely to the close collaboration between the forestry science and profession. This scientific and professional symposium marked the 50thanniversary of unbroken cooperation and was also dedicatedto the International Year of Forests, declared at Croatia’s proposal by the United Nations GeneralAssembly in its session held on 20 December 2006.
Forestry is a science, a profession and an artof managing and preserving forests and habitats, i.e. the entire forest ecosystem, for the purpose of providing permanentbenefitsfor the society, environment and economy. This statement, which gives a summarized definition of forestry, has been developed as a result of the multi-annual development of forestry and forestry science which has been undergoing continuous development in Croatia and this part of Europe. Unlike the majority of other scientific fields, Croatia’s forestry science and profession started developing at the same time as in the central Europe, for the justified fear of forest degradation and disappearance as a result of the uncontrolled exploitation.
Having stated the historical data on the development of Croatia’s forestry, we should put a special emphasis on the forestry experts’ activities aimed at establishing educational and scientific forestry institutions. They have laid down the foundations for today’s scientific and highereducation institutions to which the Croatian Forest Research Institute belongs.
The Croatian Forest Research Institute has entered its66thyear;today it is a modern institute comprising a number of buildings, laboratories, state-of-the-art equipment, a plant nursery and numerousfieldtrial facilities. The fact that a large number of young, highly qualified scientists work at the Institute is crucial toguarantee its survival, bright future and top-quality work.
The papers presented in this special edition provide an insight into the activities of the Croatian Forest Research Institute and numerous and diversescientific areas its scientists are engaged in.

Croatian Forest Research Institute, Boris Vrbek, PhD

Chairman of the Scientific Council

    VRBEK, Boris      ŠL
Medak, Jasnica  UDK 630* 188 (001) 5
Forests of Sweet Chestnut with Odorous Pig-Salad (Aposeri foetidae-Castanetum SativaeAss. nova) in Croatia      
Summary: This paper describes a new association of mesophilous sweet chestnut forests with odorous pig-salad (Aposeri foetidae-Castanetum sativaeass. nova) in Croatia. The association is the most frequently found at altitudes 200–400 m, which refers to sites at Zrinska and Petrova gora, or higher (up to 600 meters at Medvednica, Žumberak), in both cases in transitional positions between oak and beech or in the beech belt. It occurs on northern and eastern expositions and less steep slopes (up to 20°), which distinguish it very good from the well known acidophilous sweet chestnut forests (Querco-Castanetum sativae), which occurs at southern and more steep slopes. The most common soil type in this community is luvisol, deep and very acid to light acid, depending on subassociation.
It is characterized by considerably larger number of mesophilous species from beech forests than acidophilous and thermophilous species. Phytosociological releves were collected following the principles of standard Braun-Blanquet method.
In Phytosociological Table 1 there are 20 relevés of the association Aposeri foetidae-Castanetum sativae. Sweet chestnut is frequently accompanied by beech and hornbeam in the tree layer. Oak is also frequent but without important and significant role that it plays in acidophilous chestnut forests. Sometimes there are cherry, lime-trees and flowering ash in the tree layer and often silver birch in the localities with more light related to chestnut decline.
In the shrub layer, together with chestnut and beech, frequent and well developed are species from order Fagetalia and alliance Carpinion betuli: Corylus avellana, Carpinus betulus, Prunus avium, Crataegus monogyna, Acer campestre, Rosa arvensis and Viburnum opulus. The other group are species from the order Quercetalia pubescentis:Fraxinus ornus,Ligustrum vulgareand Sorbus torminalis, which occurs very frequent. The ground vegetation layer is very good developed and made from the mixture of mesophilous species from the order Fagetaliaand acidophilous species from the order Quercetalia roboris-petraeae. Frequent and abundant are only Rubus hirtusand Pteridium aquilinumwhich reflect the instability of the forest community. Important for the association and its characteristics species are Aposeris foetida,Circea lutetianaandGaleopsis tetrahit, which as mesophilous and skiophilous well describe assosiations character.
Other species from the order Fagetaliaand the allianceCarpinion betuliare: Epimedium alpinum,Sanicula europaea,Symphytum tuberosum,Polygonatum multiflorum,Pulmonaria officinalis, Primula vulgaris,Viola reichenbachiana,Galium sylvaticum,Lonicera caprifolium,Carex sylvatica, Lamium orvala, and from the order Quercetalia roboris-petraeae:Gentiana asclepiadea,Veronica officinalis,Melampyrum pratense,Hieracium racemosum,Luzula luzuloides,Luzula pilosa. When the association is developed on the higher elevation, in the beech belt, spring aspect is expressed with a domination of theAnemone nemorosa,Dentaria bulbiferaandGalium odoratum.According to the Code of Phytocoenological Nomenclature (Weber et al. 2000), relevé No. 6 in the ninth column of Table 1 is the nomenclatural type. Two subassociations were identified: typicumandligustretosum.
Aposeri foetidae-Castanetum sativaesubass.typicumsubass. nova hoc loc is negatively distinguished typical subassociation which growes on deep luvisols and on less steep slpoes (20°). Shade-tolerant species such as Athyrium filix-femina, Dryopteris filix-mas and Circea lutetiana are dominant in abundance. This subassociation includes widely distributed, anthropogenic, poor in species number, variant Rubus hirtus. This community is very specific by its physiognomy which refers to pure chestnut stands. Shrub layer is also not developed and in the ground vegetation layer Rubus hirtuscovers often 75% of the area. Interesting species is Hypericum androsaemum, rare in Croatian Flora, but it occurs frequently at this community.
According to the Code of Phytocoenological Nomenclature (Weber et al. 2000), relevé No. 6 in the Table 1 is the nomenclatural type of the subassociation typicum. Aposeri foetidae-Castanetum sativaesubass.ligustretosum vulgarisubass.nova hoc locois more thermophilous subassociation, distinguished by differential species Ligustrum vulgare,Mellitys melissophyllum and Lathyrus niger. The subassociation is considering mixture of termophilous, acidophilous and mesophilous species rather rich in species number. It grows on less acid soils, often on carbonate substrates. According to the Code of Phytocoenological Nomenclature (Weber et al. 2000), relevé No. 12 in the Table 1 is the nomenclatural type of the subassociation ligustretosum.
AssociationAposeri foetidae-Castanetum sativaeis classified to order Fagetalia Pawl. 1928, alliance of illyrian beech forests, Aremonio-Fagion (Horvat 1938) Törek et al. 1989, suballiance Epimedio-Fagenion Marinček i dr. 1993 which refers to mesophilous and subthermophilous collin forests of Ilirija. Characteristic (Epimedium alpinum,Geranium nodosum,Knautia drymeia,Vicia oroboides) and differential (Hacquetia epipactis,Heleborus odorus,Lonicera caprifolium,Primula vulgarisandRuscus hypoglossum) species of the suballiance are more frequent and abundant in the subassociationligustretosumthan in the typicum where shade-tolerant species playing the main role.
Mesophilous chestnut forests Aposeri foetidae-Castanetum sativaeass. nova hoc loco represent the terminal phase of the chestnut forests in Croatia. Primary, it originates on deep and rich soils in most of the localities on Petrova and Zrinska gora, and secondary, from the association Epimedio-Carpinetum betuli, where chestnut occurs and become predominant because of the acidification processes in the soil (north-western Croatia, Moslavina, Slavonsko gorje).There are two possible directions of the degradation processes in these forests. First goes through the overexploitation, stamping and soil acidification to acidophilous chestnut forest. The other one, more important and present in whole range of Zrinska and Petrova gora, is exclusively conditioned by management system. A few generations after clear-cutting, mixed chestnut forest turn to chestnut monoculture with onlyRubus hirtusat the ground vegetation layer, which sometimes covers 100% of the area.

Key words: Castanea sativa; Aposeri foetidae-Castanetum sativaeass. nova; Croatia; forest communities; mesophilous chestnut forests

    MEDAK, Jasnica    ŠL
Ivanković,M., M. Popović, I. Katičić, G. von Wuehlisch, S. Bogdan  UDK 630* 165 (001) 25
Quantitative Genetic Variation of European Beech (Fagus sylvatica L.) Provenances from the Southeastern Europe      
Summary: Since the genetic diversity of European beech (Fagus sylvaticaL.) in South-East Europe (particularly for adaptive traits) is not well studied, the purpose of this paper is to determine the amount, pattern and possible causes of its adaptive genetic variability, through analysis of selected quantitative traits in a provenance trial.
Research was conducted in a provenance trial in which thirteen provenances were analyzed (Table 1). The heights of all survived plants were measured successively after the first three growing seasons at the trial site, while flushing phenology and winter leaf retention were scored in the second and third year. The preliminary analysis showed that differences between provenances in the average values of height, survival and winter leaf retention were significantly influenced by age differences between provenances (due to different time of collecting seed and initial age of seedlings in the trial – Table 1), therefore the averages for the listed properties were corrected for “additive age effect”.
Analysis of variance was conducted in order to determine statistical significance of variance components caused by the effects of provenances. REG and CORR procedures were carried out to analyze the relationships between the investigated traits, as well as between the provenance mean values and climatic variables of their source stands (Table 2).
Provenance means of real and age corrected traits are shown in figures 1, 2, 3, 4, 5 and 7. The results indicate high levels of genetic variability for all studied quantitative traits. Statistically significant differences were found between provenances (Table 3), but the real data for height, survival and winter leaf retention were impacted with their age differences. Statistically significant differentiation between provenances for height and survival were lost after the additive age effect correction.
Between provenance differences for the analyzed traits were tested by Tukey-Kramer’s test for a possible geographical pattern of genetic structure. Results indicated geographical structure for the height, survival and winter leaf retention in terms of gradual differences in the east-west direction (see Figures 3, 5 and 7). However, apparently clinal variability was primary influenced by age differences. Thus, existence of the variability cannot be confirmed. Moreover, geographical pattern disappeared after the age corrections for provenance mean heights and survival (see Figures 2 and 4).
Regression analysis of the provenance mean values and Ellenberg’s climate quotients of their source stands were shown (Figures 8, 9, 10). The aim of this analysis was to determine relationship between genetic variability and climatic variables. Weak and statistically insignificant correlations between height/survival and climate quotients were determined. The same results were obtained using real and age corrected data. These traits were under the strong influence of age differences that have accidentally been associated with the geographic position of provenances (western older than eastern). It was most probably the cause of the obtained geographic structure.
On the other hand, the age corrected values of winter leaf retention were significantly correlated with EQ’s. There was gradual (clinal) differentiation of populations in the west-east direction (the frequency of trees with dead leaves retention gradually decreased from west to east) and declining trend of trees with leaves retention associated with an increasing continentality (Figure 9). It should be mentioned that western provenances were older than eastern ones and the increase of EQ’s was moderately correlated with geographic position of provenances (EQ’s of eastern provenances were on average higher than western). For these reasons, differences between provenances in percentage of trees with winter leaf retention are more likely attributable to their age differences, rather than genetic differentiation.
Geographical structure of genetic differences between provenances was not shown for flushing phenology. Results indicate an ecotypic (random) pattern of interpopulation differences (Figure 6). There was a statistically significant correlation between provenance mean values and Ellenberg’s climate quotients (EQ’s). Provenances from wetter and cooler habitats (EQ=12-16) were later flushers. With the increase of continentality, provenances showed a trend of earlier flushing. The peak of this trend was observed at the EQ=26, after which the provenances showed a reverse trend, i.e. again flushing later (Figure 10).
Despite the fact that differentiation was not detected for traits which were influenced by age differences (height, survival and winter leaf retention), it is more likely that population differentiation in South-East Europe has ecotypic pattern that is shaped by macroclimatic adaptation. This assumption is based on similar studies by other authors (Matyas et al. 2009), but also on our own results for the flushing phenology.
It can be recommended that European beech seed zone delineation and use of its forest reproductive material should be done accordingly to ecological besides the geographic criteria.

Key words: provenance trial; growth; flushing; winter leaf retention; ecotypic variation; macroclimatic adaptedness

    IVANKOVIĆ, Mladen    ŠL
    Popović, Maja
    KATIČIĆ, Ida    ŠL
    Wuehlisch, Georg von  
    BOGDAN, Saša      ŠL
Littvay, Tibor  UDK 630* 165 (001) 38
Phenotypic Stability andAdaptability of Families of Common Walnut (Juglans regia L.) in Progeny Tests      
Summary: Common walnut (Juglans regiaL.) belongs to the most important tree species in the world. With the origin in central Asia it is widespread worldwide except in tropical and subtropical regions. Its broad applications in nourishment, medicine, pharmacology and food processing, wood and leather industry makes it one of the most valuable plant species.
The distribution of common walnut in Croatia is more a result of favorable climatic and soil conditions than the organized cultivation. In Croatian common walnut is mostly spread in the hilly terrains around Hrvatsko Zagorje around Požega, Koprivnica, Bjelovar, Daruvar, Kutina, Sisak, Jastrebarsko Ozalj; in Eastern Slavonia around Vukovar and Ilok in Baranja. In Dalmatia around Split, Drniš, and Zadar hinterland, in Primorje in the hinterland of Novi Vinodolski, Crikvenica, Senj, in Istria and part of Herzegovina.
This paper presents the results of work on the selection of individual trees and the establishment of halbsib-progeny tests, over the five-year research of quantitative and morphometric traits in progeny tests of common walnut, tested in two habitats. Research sites are located at two locations that were most suitable for testing due to the ecological and soil characteristics of selections in continental part of Croatia. These sites are: Zabrdica, under forestry office Sokolovac and Kozarevac I under the forestry office Kloštar Podravski.
The study of interaction between heritage and environment is based on the assumption that environment must be controlled (similar growing conditions) and phenotypes must be known, as done in these experiments, devoting the special attention to environmental factors. In such planned and conducted experiments, relationship between genotype and environment can be studied through so-called phenotypic stability. Analysis of phenotypic stability of common walnut families in the localities (habitats) was conducted in the model of regression analysis in which the phenotypic values (growth and fruit mass) of specific families are shown as a linear function of the environment. For the independent variable it is selected the mean value of the corresponding phenotypic characteristic of families, ie diameter growth and fruit mass of the center tree at the locality. Results are listed in Table 1, 2 and shown in Figure 4, 5.
Below average growth stability and specific adaptability to high-yield environment (Zabrdica) showed families Stain 2, 4 and 6, while Stains 12, 13 and 18 showed above average stability and specific adaptability to adverse environment (Kozarevac I). Other families showed the average stability and good adaptability to all environments (Zabrdica and Kozarevac I) (Table 1 and Figure 4).
Below average fruit mass stability and specific adaptability to high-yield environment (Kozarevac I) showed only Stain 16, while Stains 1, 3, 4, 6, 15, 17, and 18 showed above average stability and specific adaptability to adverse environment (Zabrdica). Other families showed the average stability and good adaptability to all environments (Zabrdica and Kozarevac I) (Table 2 and Figure 5).
Based on adaptation capacity and production potential of the particular genotype can be determined its use-value for plantation raising. Genotypes with good adaptation ability and high productivity are the best solution for growing the common walnut in plantations.
The research results provide a good basis for creating the Croatian variety of walnut same as the opportunities for permanent preservation of genetic resources for the common walnut.

Key words: Common Walnut; phenotypic stability; adaptability; halbsib-progeny tests.

    LITTVAY, Tibor    ŠL
Ivanković,M., M. Popović, S. Bogdan  UDK 630* 232.3 (001) 46
Acorn Morphometric Traits and Seedling Heights Variation of Pedunculate Oak (Quercus robur L.) from the Seed Stands in Croatia      
Summary: Seed zone delineation of pedunculate oak in Croatia was done according to ecological differences, stand productivity and administrative borders of Forest Range Offices (NN 107/08). Oak forests are divided into three seed zones and it is recommended to transfer reproductive material only within zones. Seed delineation was preformed due to Croatian Forest Reproductive Material Transfer Law (NN 75/09) that was aligned with EU Directive on forests reproductive material (1999/105/EC). Seed delineation should be done according to genetic differences between various zones i.e. provenance regions. Aiming at verification of current seed zones in Croatia, and on the basis of general knowledge on pedunculate oak genetic variation, research on genetic variation of the species in Croatia has been started. Due to that, seeds were collected within so called registrated seed stands which are normally used as a seed sources for regeneration of managed oak stands.
Results of the study of seed morphometric analyses are presented in this paper. Seed were collected during autumn 2006 below 25 trees within each of 17 seed stands that represented whole distribution range of the species in Croatia (Table 1). 30 acorn from each tree were sampled for morphometric analysis and measured the height of seedlings. Acorn length, widths and masses and seedlings height were measured and acorn volumes were calculated according to formula for cylinder volume (Figure 1, 2).
ANOVA was performed by MIXED procedure in SAS, in order to analyze significance of various effects. Results showed that current seed zones were not statistically significant effect (there were no significant differences between them), but there were significant differences between populations within zones, as well as between trees within populations (Table 2). Table 3 shows Type 3 significance F-test for fixed effect of populations within seed zones for studied acorn traits and for one-year seedling height.
Determined populations differences did not match current seed delineation i.e. there were no obvious geographic pattern in between population variability for studied acorn traits as well as analyzed seedlings traits. Tukey-Kramer’s test was performed to determine the form and the differentiation which populations are separated statistically significantly. Test did not give results from which we could observe regularity in the geographical separation of populations for analyzed seedlings traits (Table 5). Population HR 88 (Lacići-Gložđe, Koška) was significantly differed from the geographically closed population HR HR 58 (Darda), HR 577 (Poljadijske šume, Požega) and HR 627 (Repaš), while at the same time did not differ from the distant population (HR 387 – Karlovac, Rečićki lugovi and HR 609 – Buzet).
Statistically significant differences between populations for all analyzed traits clearly indicate the genetic differentiation of oak populations. However interpopulation differentiation did not correspond to the geographical pattern. Specific character of differentiation indicates ecotypic pattern of genetic differences between oak populations in Croatia, i.e. differentiation that are caused by adaptation to specific micro-enviromental conditions (e.g. humidity, temperature and edaphic features). To confirm the hypothesis of ecotype pattern of genetic diversity is necessary to conduct additional research in genetic tests (provenance and progeny tests). Differences between currently seed zones were not statistically significant for any of the analyzed traits, which has not confirmed valid justification of current seed delineation. Nevertheless, it should be noted that the analysis of seed morphometric traits are not adaptively valuable properties, while the results of the one-year seedling heights are not sufficiently reliable due to a very early age of plants. Therefore these results should be regarded only as a stimulus for further research of oak genetic diversity in Croatia.

Key words: seed delineation; provenance region; morphometric traits; acorn; seedling heights; seed zones

    IVANKOVIĆ, Mladen    ŠL
    Popović, Maja
    BOGDAN, Saša      ŠL
Marjanović,H., M. Z. Ostrogović, G. Alberti, I. Balenović, E. Paladinić, K. Indir, A. Peressotti, D. Vuletić  UDK 630* 120 + 114.2 (001) 59
Carbon Dynamics in younger Stands of Pedunculate Oak during two Vegetation Periods      
Summary: Net Ecosystem Productivity (NEP) and Net Ecosystem Carbon Balance (NECB) of young Pedunculate oak (Quercus roburL.) stand were investigated. Two independent methods for assessing NEP were used: a) micrometeorological method of Eddy covariance (EC) and, b) combination of biometric method for assessing Net Primary Productivity (NPP) and periodic soil respiration (SR) measurements (named for reasons of brevity the combined method). NEP from combined method was obtained as a difference of NPP and heterotrophic respiration (Rh) which was estimated to have 50% share in the measured total SR.
Maximal measured daily NEP from eddy covariance was 10,7 gC m-2 day-1in 2008., and 12,2 gC m-2day-1in 2009. The annual NEP ranged from 384 gC m-2yr-1in 2008 to584 gC m-2yr-1in 2009 indicating that the stands around the EC tower were actively storing carbon during both years.
From biometric measurements of stem increment using dendrometer bands, height increment and litter production we obtained an average NPP of the stands in the footprint of 777 gC m-2yr-1in 2008 and 846 gC m-2yr-1in 2009. Heterotrophic respiration (Rh) , estimated from SR measurements was 438 gC m-2yr-1in 2008 and 441 gC m-2yr-1in 2009. By subtracting Rhfrom NPP, we obtained NEP of 339 and 405 gC m-2yr-1in 2008 and 2009, respectively.
Comparison of results for NEP during vegetation season reveals that agreement between the two methods was very good until July for both years. Later in the summer and autumn, discrepancy occurs when stem growth ceases but trees continue to actively store carbon. This leads to the underestimation of NEP from combined method during that period, leading to the overall lower values of NEP when compared with NEP values from eddy covariance. There could be several reasons for the discrepancies namely, share of Rhin total SR could be less than 50 %, R:S could be higher than 0.257, or various combinations of both. Further research is needed that would provide better estimates of share of Rhin SR, R:S ratio and soil carbon content.

Key words: Eddy covariance method; soil respiration; carbon fluxes; carbon sequestration

    Marjanović, Hrvoje
    OSTROGOVIĆ, Maša Zorana    ŠL
    Alberti, Giorgio  
    BALENOVIĆ, Ivan    ŠL
    PALADINIĆ, Elvis    ŠL
    INDIR, Krunoslav    ŠL
    Peressotti, Alessandro  
    VULETIĆ, Dijana      ŠL
Dubravac,T., S. Dekanić,V. Roth  UDK 630* 425 + 531 (001) 74
Damage Dynamics and Structure of the Pedunculate Oak Tree Crowns in Stands in Microelevations and Microdepressions – Results from the Monitoring on Permanent Experimental Plots      
Summary: The crown damage of a tree has a very prominent place among the broad spectrum of factors defining the pedunculate oak (Quercus roburL.) decline and dieback, largely due to the fact that it represents the first visible symptom of the decline in tree‘s vitality. Besides, crown damage is a key factor for the selection of trees with high risk of dying during the sanitary and salvage cuttings, in order to salvage high value timber that would be otherwise lost or severely degraded when the tree dies. Aim of this contribution is to investigate dynamics of crown damage of pedunculate oak trees, as well as the effect of the crown damage on tree’s basal area increment during longer time period in two most important types of pedunculate oak forests in Croatia. Research was done on permanent experimental plots situated in the stands of pedunculate oak and common hornbeam (II-G-10) and stands of pedunculate oak and Genista elata (II-G-20). In total, 38 permanent experimental plots were used, out of which 13 were re-measured with intervals of 9 to 17 years (Table 1). In first measurement, all trees on plots were permanently tagged, and map of tree locations and crown projections was made. Trees were measured for diameter at breast height (DBH), total tree height and height to crown base. Crown length was calculated as the difference between the total tree height and height to crown base, while the crown ratio was calculated as the ratio of crown length and total tree height. From the map of horizontal crown projections the average crown width was calculated as a mean of the maximal and minimal crown diameters. Assessment of the crown damage was done according to the methodology of the ICP Forests Programme, whereby the trees were tallied into following five crown damage (CD) classes: 0 (< 10 % CD), 1 (11-25 % CD), 2 (26-60 % CD), 3 (61-99 % CD) and 4 (100 % CD – dead tree). For some analyses trees were further grouped into two classes: healthy trees with crown damage of 25 % and less, and severely damaged trees with crown damage over 25 %. Results from this research are, however, not comparable to the damage assessment reports of the ICP Forests because of the different sampling strategies. On 13 plots the second measurement was made in which DBH of all trees still present on the plot was recorded, and the crown damage was assessed according to the same methodology used in the previous measurement, and furthermore, by the same observer. Average basal area increment per year (cm 2 year-1) per tree was obtained by dividing tree’s total basal area increment by the interval (number of vegetation periods) between the two measurements. Total number of oak trees analyzed was 749 and 540 in first and second measurement, respectively.
Prior to the crown damage analyses, the basic structural features of the stands on re-measured plots, as well as morphological features of pedunculate oak trees in two forest types were analyzed (Table 2 and Figure 1). Stands of the forest type II-G-20 have much larger shares of oak trees in the total number of trees, and total stand basal area compared to the type II-G-10. oak trees in both types exhibit the same relation of tree height (Figure 1A) and crown width (Figure 1D) to DBH, but the crown length (Figure 1B) and crown ratio (Figure 1C) are higher in the forest type II-G-20. Reason for this lies probably in the effect that common hornbeam trees in the lower canopy layers have on the morphological development of oak trees in the stands of II-G-10 type, while the stands in the II-G-20 have almost no sub-canopy layers.
Relationship between the share of oak trees with severe crown damage (> 25 %) and stand age was examined for the 33 plots of forest type II-G-10 spanning almost entire rotation length of pedunculate oak forests in Croatia (II. to VII. age class). Linear regression with logarithmic transformation of independent variable (stand age) was used for this analysis. According to the model, significant increase of severely damaged trees occurs after the stand age of 70 years (Figure 2A). The stands in the type II-G-20 departed significantly from the model in the first measurement, with only 26 % of severely damaged trees compared to 76 % in stands of II-G-10. By the second measurement, however, these plots also conformed to the behavior predicted by the model (Figure 2B), due to the deterioration of the overall crown condition.
Distributions of oak trees by the CD classes in two measurements (Figure 3) reveal the direction of the crown damage dynamics, which is in more detail presented in the Figure 4. In both forest types, the change in crown class of the oak trees was predominantly in the direction of the worsening crown health status. Negative trend is more pronounced in the II-G-20 forest type. According to the CD classes recorded in the first measurement (Figure 5), decline intensity was most pronounced in the CD class 3, from which 70 % and 50 % of trees in forest types II-G-10 and II-G-20, respectively, died off by the second measurement. This result provides further foundation for the use of the CD assessments in the day-to-day forestry as a reliable indicator of the tree’s imminent death.
Effect of crown damage on the basal area increment of oak trees was examined through: (i) the regression analyses of basal area increment per year per tree over DBH (Figure 6) and crown width (Figure 7), comparison of distributions of healthy and severely damaged trees over basal area increment classes (Figure 8), and by comparison of median values of basal area increment of healthy and severely damaged trees by forest types and stand age classes (Figure 9). Crown damage was found to have a significant impact on the basal area increment of pedunculate oak trees, with severely damaged trees having significantly lower basal area increment compared to healthy trees of the similar dimensions. These differences were very similar for both forest types.

Key words: pedunculate oak; crown damage; stand structure; crown structure; significant crown damage; basal area increment; II-G-10; II-G-20

    DUBRAVAC, Tomislav
    DEKANIĆ, Stjepan      ŠL
    ROTH, Valentin    ŠL
Seletković,I., N. Potočić,V. Topić, L. Butorac, G. Jelić,A. Jazbec  UDK 630* 232.3 Pinus nigra Arn. (001) 90
Influence of Various Container Types and Slow-release Fertilizer Doses on Growth and Physiological Parameters of Black Pine (Pinus nigra Arn.) Seedlings      
Summary: Although growing of conifer seedlings in containers is nothing new, our knowledge is deficient when it comes to various combinations of substrates, container types and different fertilizers and fertilizer doses, especially with tree species aimed at planting in the coastal zone of Croatia.
This paper presents the results of the experiment testing the influence of various types of containers and doses of slow-release fertilizer (Osmocote Exact Standard 5–6 M) on the growth and physiological parameters of Black pine (Pinus nigraArn.) seedlings.
The trial was set up in the nursery Omiš, Hrvatske šume d.o.o. Zagreb, as a randomized block in four repetitions. Treatments were different container types (HIKO V–150, HIKO V–265, QPD 12T/18) and fertilizer doses (2,4 or 6 g/l of substrate). Concentrations of nitrogen, phosphorous, potassium, calcium, magnesium were determined in the needles of seedlings. Seedling heights and root collar diameters were measured at the end of the first vegetation season, and root traits were analysed with software package WinRhizo.
Fertilization with Osmocote Exact had an influence on concentrations of mineral nutrients in black pine needles. The most marked positive influence of fertilization can be seen in nitrogen concentrations in needles (Fig. 1). With phosphorous the concrentrations were rising with dose especially in HIKO V–150 containers (Fig. 2). Fertilization had a negative influence on calcium concentrations, but the deficiency of calcium was not established, regardless of applied fertilizer dose (Fig. 4).
Both dose and container type influenced significantly the development of height and root collar diameter of seedlings (Table 3, Figs. 6 and 7). Maximum height and root collar diameter of seedlings were recorded in HIKO V–265 containers at the highest fertilizer dose. With HIKO V–150 containers the highest dose will favor height growth at the expense of root collar diameter. The type of container was decisive for the development of roots. Fertilizer dose had a significant influence on lenght and volume of roots, but not on the number of fine roots or number of root tips. The influence of fertilizer on fine root development is most pronounced with HIKO V–150 containers, where seedlings fertilized with the largest dose developed the highest number of active roots in comparison with other container types.

Key words: black pine (Pinus nigraArn.); containers; Osmocote Exact Standard 5–6M; seedling height; root collar diameter; nutritional status; WinRhizo

    SELETKOVIĆ, Ivan      ŠL
    POTOČIĆ, Nenad      ŠL
    TOPIĆ, Vlado      ŠL
    Butorac, Lukrecija
    JELIĆ, Goran    ŠL
    Jazbec, Anamarija
Krpan, A. P.B., Ž. Tomašić, P. Bašić Palković  UDK 630* 537 + 562 (001) 103
Biopotential of Indigobusch (Amorpha fruticosa L.) – Second Year of Investigation      
Summary: Recent studies of biomass in Croatia were directed towards commercial forest species. Besides trees, building elements of our natural forests are also various shrubs and ground vegetation. It is assumed that, because of the increasing market demand, the biomass of trees but also some of the other components of forest biomass will be commercially interesting in the near future. One of them is Indigobush (Amorpha fruticosaL.), a North American shrub, which can be found, in the areas of our lowland forest ecosystems since year 1900, making natural regeneration of stands even more difficult or often preventing natural regeneration. Today, Indigobush expands to the habitat of lowland forests and in riparian forest of oak and broom (Genisto elatae-Quercetum roboris Ht. 1938), especially in sub associations with trembling sedge (Genisto elatae-Quercetum roboris caricetosum brizoides Ht. 1938) and remote sedge (Genisto elatae-Quercetum roboris caricetosum remotae Ht. 1938) (Matić2009). According to present research, Indigobush is the most common in the Posavina region.
This paper shows the results of the second year of study in Indigobush biopotential as a part of six-year-long experiment in a natural stand of Indigobush in the forest Management Unit Posavina, Department 126a, Forestry Sunja, FA Sisak.On the harvested area in the year 2008, four field experiments were established with six plots measuring 5 x 5 m each.Plots are marked form1 to 6.Numbering indicates the length of rotations for Indigobush as well as rhythm of measurements and harvesting on the plots. In the second year of the project survey sample plots 1 and 2 were included, which position in the experimental fields can be seen in Figure 1. Ways of filed survey, sampling and data processing are described in the chapter Materials and Methods. The results of the field measurements on the plots are shown in Figures 1 to 4, in which positions of Indigobush stumps and values related to Indigobush sprouts can be seen.The number of annual sprouts on plots nr.1 ranges from 276 to 455 and two-yearold sprouts on plots nr. 2 ranges from 265 to 432. Converted to hectares, number of sprouts is 106,000 to 182,000.Medium height of annual sprouts on plots nr.1 is from 2.13 m to 2.25 m, and heights of two-year-old sprouts on plots nr. 2 are form 2.28 m to 2.58 m. The mean diameter of sprouts on plots nr. 1 ranges from 7.0 mm to 7.6 mm, and on the plots nr. 2 it ranges form 9.1 mm to 10.5 mm.At the annual sprouts the largest diameter recorded was 14 mm and maximum height was 3.4 m, and at the biennial sprouts it was 20 mm for maximum diameter and 3.7 m for maximum height. In proportion to the number and size of the Iindigobush sprouts mass of wood substance on plots nr.1 ranges from 23.29 kg to 38.14 kg, on the plots nr.2 from 54.34 kg to 78.55 kg. Given the uniformity of height and diameter growth and increment, we find that the production of Indigobush biomass is in direct correlation with the number of sprouts per unit area.In the second year, height increment is reduced (compared to the first year), the mean diameter increases from 2 to 3 mm, stem branches, starts flowering and fruiting.Table 1 shows green mass on the surface, green mass per hectare, the proportion of moisture or dry weight in green mass and dry wood substance produced on the plot and per hectare for plots 1 and 2 in the field experiment. In two-year-old Indigobush stand, production of green and dry biomass is twice as high (24.52 to 11.96 t/ha or 16.39 to 7.87 t/ha) compared to the biomass of annual stand of other vegetation.In the first vegetation period, after felling old Indigobush, the annual production of green biomass was 15.20 t/ha (Krpanand Tomašić2009), and in the second period was 11.96 t/ha or 3.24 t/ha less, indicating a decrease of Indigobush’s biopotential at repeated annual cutting on the same surface.One third of the green mass goes to moisture and two thirds go to dry matter, which places Indigobush, cut out of vegetation period, commercially favorable for biomass energy.
In Table 2, data on seed collection from the plots number 2 of field experiments from 1 to 4 is shown. On the plots it was collected from 3.20 kg (field 3) to 4.94 kg (field 1) or an average of 3.97 kg, so the weight of seed per hectare at the time of collection ranged from 1.280 kg to 1.976 kg or an average of 1.589 kg.Seed moisture content ranged from 14.3 % to 15.7 % or an average of 15.2 %, a mass of dry seeds ranged from 1,082 kg/ha to 1,674 kg/ha, or an average of 1,348 kg/ha.First crop confirmed earlier findings of an abundant yield of Indigobush. Table 3 shows data of green and dry mass of Indigobush wood on plots nr. 2, for which the values of wet and dry seed mass have been added. With moisture content W = 34.2 % the energy value of Indigobush biomass is 12.727 MJ/kg, and at W0 = 20.259 MJ/kg (Marosvölgyiet al. 2009).Very close mean values of moisture content obtained in our study (Table 1) and data of produced biomass (Tables 1 and 3) show us ability to assess the energy value of Indigobush biomass.ld be noted that the Indigobush biomass in our lowland forests forms naturally without any agricultural practice and associated costs. Including Indigobush biomass into alternative energy flows brings multiple benefits and development opportunities. We think that this would significantly increase the amount of available forest biomass in Croatia, would have widened the range of forestry products, would reduce the cost of regeneration of lowland forests, and residents of rural and urban gives up the possibility of earning an income related to the cultivation and harvesting of Indigobush biomassas well as introduction of biomass power plants.

Key words: Indigobush; bioproduction; energy value; lowland forest ecosystems; Croatia

    KRPAN, Ante P. B.    ŠL
    TOMAŠIĆ, Željko    ŠL
    Bašić Palković, Pavao
Pernek,M., N. Lacković  UDK 630* 453 (001) 114
The Role of Bark Beetles in Silver Fir Decline and Possible Use of Pheromone Traps for the Monitoring      
Summary: Silver fir is the most important coniferous species in Croatian forestry, but in the same time the most threatened whose strong decline occurs periodically.Recent decline in Croatia was registered in the year 2003, especially in Lika and Gorski Kotar, with strong attack of fir bark beetles.This beetle gradation is connected with the three known Pityokteines species in Croatia: P. curvidens, P. spinidensandP. vorontzowi.The aim of this work was to determine what impact bark beetles have on the decline of Silver fir.For this purpose pheromone traps were placed in Litoric (Gorski Kotarmiddle Croatia), for monitoring through the vegetation periods from 2004to 2010. In addition, in 2007the effectiveness of different trap systems was tested. The commonly used Theysohn trap with dry container was modified through locking the container so liquid that was previously put in it couldn’t efflux. A pheromone mixture named Curviwit ® was used which is used for individuals baiting of fir bark beetle species Pityokteines curvidens.
The results during the seven year monitoring period show clearly visible connection between fir bark beetles and fir decline (Figure 1). The largest catches in pheromone traps were measured between 2005 and 2007,when the most injured trees were felled in the forests.Most catches, about 94 %, throughout the year of monitoring occur in April and May (Figure 2 and 3), which concludes that traps should be placed only in those months. The test results of dry versus wet traps show that more important catch is achieved by modifying Theysohn traps to wet traps (Figure 4).
On the basis of calculating the abundance of bark beetles ofP. spinidens andP. curvidensin the trunk (Table 1) and the use of maximum mortality rates of 70 %, from previous studies biological potential of these insects was simulated.One infected 90 year old fir tree is directly threatening 50-60 trees in the next years.This result demonstrates the enormous potential of the silver fir bark beetle species. Because of the need to reduce the population of bark beetles, use of pheromone traps for monitoring should be considered as one action for effective preventive and sanitary measures in protection of forests.

Key words: Pityokteines spinidens; P. curvidens; P. vorontzowi; Abies alba; pheromone traps

    PERNEK, Milan      ŠL
    Lacković, Nikola
Liović, Boris  UDK 630* 443 (001) 122
The Influence of Powdery Mildew (Microsphaera alphitoides Griff. et Maubl.) on Growth and Survival Rate of Oak Seedlings      
Summary: Powdery mildew as plant disease caused by the fungus species Microsphaera alphitoidesGriff et Maubl., has major impact in process of oak trees dieback. Most threatened are seedlings and saplings. Experiences from professionals in last few decades proved that within the habitat of Pedunculate oak, powdery mildew is one of important factors that affects survival rate of oak’s saplings, therefore rejuvenation of oak forests. Although fungus highly pathogenic, the researches of its influence on development and dieback of saplings in order to justify the investments in protection are relatively few. The researches targeted to determine the level of dependence between the height increment and diameter increment in relation with the survival rate of seedlings and the intensity of contamination caused by mildew, are set on research plots according to the block distribution in fenced surfaces, under the Forest District Bjelovar of the Croatian Forests Ltd. The experiment is set on the same model also in the Croatian Forest Research Institute’s nursery. The acorns collected were treated with fungicides and sawn in rows in fenced surface. In experiment two variants were tested in four repetitions; seedlings treated with anti-mildew fungicides and seedlings without any protection. After germination in one-month intervals the plots were cleaned from weed and the height increment was measured, whilst based on the surface of leaves covered with mycelia the infection caused by powdery mildew was estimated on 50 leaves sample in every plot. Fungicides were applied every 15–20 days depending of weather conditions. For the protection three fungicides were used: Artea 330 EC (0.5 l / ha), Anvil 5 SC (0.5 l /ha) and Punch 10EW (0.3 l / ha) all with 250 l/ha of water and 0.2 % Sandovit surfactant. Fungicides were used in forest nurseries seven times and five times in forest. The intensity of photosynthesis was measured on infected and non-infected leaves with portable gas-exchange system Li-Cor LI- 6400. On seedlings treated with fungicides at 10.00 hours was measured 8,31 µmol of CO2m-2s-1while at 14.00 hours was measured 6,76 CO2m-2s-1. On infected seedlings at 10.00 hours was measured significantly lesser value 5,38 µmol of CO2m-2s-1while at 14.00 hours 3,75 CO2m-2s-1. The research results show the direct relationship between the infestation by powdery mildew and the intensity of photosynthesis with the height increment and the survival rate of seedlings. This relationship is particularly denoted inside the forest, under the canopy where average height of seedlings (Graf 4) is significantly lesser at the infected seedlings (22,62 cm) compared with the seedlings treated by fungicides (25,57 cm). At the infected seedlings appeared massive defoliation 12 days earlier than at the uninfected. The survival rate of infected seedlings (Graf 7) in the forest at the end of the 1st year is 78 % while the survival of treated seedlings is 94 %. In opposition inside the nursery (Graf 5) the infected plants have average height of 24,82 cm at the end of first vegetation, while treated are relatively smaller 22,56 cm. The survival rate in the nursery (Graf 6) is approximately equal in both treatments, at the infected seedlings 92 % comparing to 95,5 % at the uninfected.

Key words: oak seedlings; powdery mildew (Microsphaera alphitoides Griff. et Maubl.); fungicides; photosynthesis intensity; survival rate; height increment

    LIOVIĆ, Boris    ŠL
Pernek,M., M. Županić, D. Diminić,T. Cech  UDK 630* 443 (001) 130
Phytophthora Species on Beech and Poplars in Croatia      
Summary: The genus Phytophthora, belongs to the Oomycota, parasitizes on many species of woody plants, causing decay of roots which is often followed by climatic extremes. Phytophthora spores can survive in soil for several years waiting for optimal conditions for germination, zoosporangium is formed, from which zoospores are released. The zoospores are chemotactic swimmers which actively find tree fine roots that become infected. The disease develops over a long number of years, but certain factors can significantly speed up the decline of trees. Bleeding lesions on the trunk (Figure 1–3), increasing of the amount of dead branches, and lack of lateral shoots are typical symptoms ofPhytophthorainfection which was registered on two different tree species in Croatia (Fagus sylvaticaandPopulus x euroamericana). The consequence was a reduction of surface of leaves or the decline of vitality, and ultimately death of the tree. Given the importance of the problem in the world, and the potential dangers of Croatian forests, the aim of this study was to determine the presence of Phytophthora species in Croatia, and to assess the threat of their expansion. Investigations were carried out in Bjelovar and Osijek area in beech and poplar euro-american clones (Table 1). Samples of bark and soil were taken from trees with clear symptoms of the disease, and analysed in the laboratory. Parts of the samples were transferred to culture media (PDA, V8), and molecular analysis of suspected isolates was performed (Figure 5). Soil samples were processed by immersing in water, and pears, young leaves of oak, rhododendron young leaves and fresh apples were used as baits. The obtained samples were processed by surface sterilization and placed on several types of culture media, as mentioned above. Obtained pure cultures (isolates) were analyzed by molecular tehnics.
The results show that the presence of P. cambivorawas confirmed on beech andP. cambivoraandP. ganopodyideson poplar. The occurrence of P. cambivorais related to changes of extreme dry and wet periods (Figure 6). The results on poplars shows that clone 275/81 have been significantly damaged by species ofPhytophthora.

Key words: Phytophthora; root decay; beech; poplar clone

    PERNEK, Milan      ŠL
    ŽUPANIĆ, Miljenko    ŠL
    DIMINIĆ, Danko    ŠL
    Cech, Thomas    
Pilaš,I., Š.Planinšek  UDK 630* 116 + 114 138
The Reconstruction of the Water Regime in Lowland Forests in Support of Sustainable Management      
Summary: Amongst the existing forest types in Europe, the specific biological function of water is nowhere more distinctive than in the lowland forest ecosystems. Consequently, no existing forest types are more shaped by historic hydrologic conditions, altered by manmade deviations from the natural water regime and vulnerable to consequences of global warming. The lowermost parts of the lowland forests, the wetlands, present the transitional zones between terrestrial and aquatic ecosystems i.e. ponds, lakes, streams and rivers. Nowadays, due to excessive urbanization and the spread of agriculture, the total area of lowland forests and wetlands has been significantly reduced. One of the largest complexes of alluvial floodplain wetlands and lowland forests in Europe are situated in the South-East Europe, in the Sava and Drava River basins, tributaries to the Danube River. The Sava River is a unique example of a river where the floodplains are still intact, supporting both flood alleviation and biodiversity. Continental lowland forests in Croatia cover an area of more than 200.000 ha with a significant role in forestry production, flood reduction, recharging groundwater reserves, as well as filtering pollutants. The natural forest vegetation consists of mainly hardwood tree species such as the common oak (Quercus roburL.), field ash (Fraxinus excelsior Vahl.), common hornbeam (Carpinus betulus L.) and softwood species such as black alder (Alnus glutinosa(L.) Geartn.), poplars (Populussp.) and willows (Salixsp.). For the biological diversity of lowland forests and attached wetlands is strongly important specific combination of hydrology and soils. The development of these forests in history was determined by regular seasonal alternations of groundwater tables (hydro period) and periodic flooding. This paper presents the possibilities for the re-establishment of the water regime of lowland forests as one option to reduce the impact of climate change in the future. To reduce negative impacts of anthropogenic alternations in the groundwater regime from the past and to attenuate slow down future very possible prolongation of droughts and water scarcity in the lowlands, various forest managerial and engineering practices could be considered. Basically, there are potentially two main contrasted measures of soil water balance manipulation: drainage of soils (through drainage ditches and channels) which contribute to decreasing the groundwater tables and forest management i.e. (tendering and thinning) which contribute to increased soil water content and increase in the groundwater level. Through these water table management practices, the amount of soil water required for the survival of lowland forests could be maintained to some degree to attenuate the negative hydrologic trends and natural hazards such as droughts. The comprehensive methodological review of activities that must precede such reconstruction activities are presented. As the initial segment all the major components of floodplain ecosystems – the morphology of the terrain, hydrography, soils stratigraphy, vegetation and anthropogenic influences – should be assessed. As a next step methodological options towards how to obtain the knowledge of the natural water regime prior anthropogenic hydrotechnical activities which caused the creation of the ecosystem in its current form are presented. For this purpose the morphology of hydromorphic soils i.e. relict indicators of natural water regime in lowland habitats are assessed. The next step includes the spatial determination of critical areas or hot spots, threatened by excessive falls in the groundwater level on which specific measures can be applied to return to natural water regime conditions (i.e. water retention in dry riverbeds).

Key words: Lowland forests; water regime; groundwater; relict indicators; soil morphology; hydro-technical measures

    PILAŠ, Ivan      ŠL
    Planinšek, Špela  
Potočić,N., I. Seletković  UDK 630* 533 + 425 149
Defoliation of Forest Trees in Croatia in the period 2006 – 2009      
Summary: In response to widespread concern that air pollution could affect forest condition, the International Co-operative Programme on the Assessment and Monitoring of Air Pollution Effects on Forests (ICP Forests) was established by the Convention on Long-range Transboundary Air Pollution (CLRTAP) under the United Nations Economic Commission for Europe in 1985. Croatia joined the Programme in 1987. The advantage of monitoring is in obtaining a time series of data that enables correct deduction on the phenomena that, in this case, vary on annual basis.
Monitoring is conducted on two networks: Level I (so called bioindication plots at 16 x 16km distance) and basic network (4 x 4 km distance of plots). Defoliation, the key parameter for assessing forest ecosystem condition, is assessed according to ICP Forests Manual on methods and criteria for harmonized sampling, assessment, monitoring and analysis of the effects of air pollution on forests.
Defoliation is high in Forest Branch Offices Vinkovci, Zagreb, Delnice and Buzet, and low in Bjelovar and Koprivnica (Fig. 5). The high percentage of moderately to severely damaged trees in Forest Branch Office Delnice and Vinkovci is the result of intensive dieback of silver fir and pedunculate oak, respectively. In Forest Branch Office Buzet, a high percentage of moderately to severely damaged trees is the result of high defoliation values in almost all surveyed species.
In Forest Branch Offices Gospić and Senj, moderate to severe damage of silver fir trees in year 2009 is significantly lower that the corresponding value in the bioindication and basic plot network in Croatia, while it is somewhat higher in Forest Branch Offices Delnice and Ogulin.
Very high values of percentages of moderately to severely damaged trees of pedunculate oak in the year 2009 were present in Forest Branch Offices Požega, Zagreb, Našice and Osijek, and very low in Bjelovar and Koprivnica. Moderate to severe damage of beech is significantly higher than the value for Croatia in Forest Branch Offices Zagreb, Delnice and Senj, and lower in Bjelovar, Sisak, Karlovac and Našice.
The rising percentage of moderately to severely damaged trees of all species started in 2002, and for broadleaves in 2003. Conifers, on the other hand, have a decreasing trend of defoliation since 2006 (Tabs. 2–4).
Keywords: ICP Forests, condition of forest ecosystems, crown defoliation, Level I and basic network

    POTOČIĆ, Nenad      ŠL
    SELETKOVIĆ, Ivan      ŠL
Roth,V., S. Dekanić,T. Dubravac  UDK 630* 232.3 (Quercus robur L.) 159
Effect of Acorn Size on Morphological Development of One-year-old Seedlings of Pedunculate Oak (Quercus robur L.) in Differing Light Conditions      
Summary: Increase of the share of high-quality seedlings in the total production on the one hand enhances the production efficiency of the nursery production, and on the other hand improves the probability for successful planting in the field. The quality of the seedlings after the first growing season is related to the quality of the seeds used. In the tree species with large seeds, like pedunculate oak (QuercusroburL.), quality is related to the size of the seed, i.e. the amount of stored nutrients. Therefore, the aim of this contribution is to evaluate the effect of acorn size on the morphological development of pedunculate oak seedlings during the first growing season under contrasting light regimes.
In total, 891 visually healthy acorns collected in the certified seed stand were planted in the “Bosnaplast” containers filled with peat (Figure 1). Part of the containers were kept in the shade of about 10 % of full light during the whole experiment. Before sowing, diameter, weight and length was measured on subsample of 200 acorns. Regression analysis showed that the acorn mass as the most important predictor of the nutrient content much more depends on the acorn diameter, than on the acorn length (Figure 2). Therefore, three acorn size classes were formed according to distribution of the acorn diameters: small acorns (. 16 mm of diameter), medium-sized acorns (16,1 mm to 17,9 mm of diameter) and large acorns (. 18 mm of diameter). During the sowing, acorns were measured for diameter and grouped into three classes of acorn size. Position of each acorn was recorded within the container and each container was labeled to facilitate the connection between the measurements of the acorn size and the subsequent measurements of the emerged seedlings. Subsample of 25 seedlings was removed from the experiment with fully developed leaves for detailed measurements of leaf area, and allocation patterns of dry biomass into three plant compartments: leaf, root, and stem. After the first growing season, height and root collar diameter were measured on all emerged seedlings.
Effect of acorn size and light regime on morphological features of one-year old seedlings of pedunculate oak were examined with the analysis of variance. Following morphological features of seedlings were tested: height (Figure 3A and Table 1) and root collar diameter (Figure 3B and Table 1) of the seedlings, leaf area (Figure 4A and Table 2) and specific leaf area (Figure 4B and Table 2) of the seedlings, dry weight (Figure 5A and Table 3) and ratio of aboveground:underground dry weight of the seedlings (Figure 5B and Table 3).
In seedlings grown in full sunlight increase in the acorn size resulted in the increase in average height and root collar diameters of the seedlings, average leaf area of the seedlings, and seedlings total dry weight. Specific leaf area was, on the other hand, smaller in seedlings from larger acorns. For the seedlings in the shade, light was the decisive factor influencing their morphological development, but still the seedlings from larger acorns were higher and had larger root collar diameters compared to the seedlings from smaller acorns.
According to the results obtained in this research, it is safe to say that there is enough space for the improvements in the nursery production of pedunculate oak seedlings by taking into account the size of the acorns. However, further detailed research efforts are needed to deduce final conclusions and recommendations for the practical nursery production.

Key words: pedunculate oak; acorn size; light; one-year-old seedlings; nursery production

    ROTH, Valentin    ŠL
    DEKANIĆ, Stjepan      ŠL
Gradečki-Poštenjak, M., S. Novak Agbaba, R. Licht, D. Posarić  UDK 630* 232.3 169
Dynamics ofAcorn Production and Quality of English OakAcorn (Quercus robur L.) in Disrupted Ecological Conditions      
Summary: Pedunculate oak is a climatogenic species and it constitutes principal forest communities. If some ecological factor in its habitat is altered, due to unfavorable biotic and abiotic factors, common oak cannot adjust fast and it suffer substantial damage over the years. Current ecological imbalance can be recognized as main reason in oak dieback. Deterioration sings become visible and they are reflected in decline of tree vitality, unsettled and low yield and also remote natural forest regeneration.
Variability in acorn production is the result of sin ecological and genetic factors. Acorn yield is the most influenced by maternal trees. Pedunculate oak belongs to subgenus Lepidobalanus and has tendency of periodical yield, with return of every 4 years (abundant), and every 2 years (normal).
Research on acorn production have been carried out in “Spačvanski bazen” area in period from 2006 to 2010. Main research goal was to monitor acorn crop according to quality and quantity, in stands of different age - middle aged, older and old forests, so production potential could be identified.
Experimental plots were established in 2006. (Tables 1 and 2). Acorn production assessment- acorn growth and development, was monitored by cone-shaped acorn-collecting traps method. Acorn-collecting traps were placed beneath the canopy of selected trees of different crown damage classes. In the crop years acorns were collected, and in the spring next year seedlings were counted. Collected materials were analyzed in the Laboratory for testing seed quality. Seed quality was tested accordingly to ISTA methodology.
Monitoring of growth and development of acorns by acorn-collecting traps method (Table 3) proved the fact that most matured and normally developed acorns came from older stands, and the least in old stands. Regarding crown damage degrees the most matured acorns came from crown damage class 2A, and least from class 2B and 3.
First acorn crop was in 2006 and second in 2010. (Tables 4 and 5). In year 2006 acorn crops was more abundant than in 2010. The best acorn crop was in old stands (on average 269 kg/ha), the worst was in middle aged forests (41 kg/ha). With reduction of tree age came reduction in acorn crop. Yield in 2010 was the best in older forests (90 kg/ha) and the worst in middle aged forests (30 kg/ha). Average number of seedlings was at its peak in old forests (40000 pts/ha), the worst in older forests (16167 pts/ha). Periodicity in acorn production during the period of 11 years in the management unit Slavir and on the area of Forest Administration Office Vinkovci followed same trend in 11 years time (Figure 1 and 2).
Annual acorn production was monitored for 11 years and crop years were: 2000, 2002, 2003, 2006 and 2010. Average quality values for acorns harvested on experimental plots were: 2006. (Figure 3)- viability 83%, insects presence 12% 1000 seed weight 5384 g, number of acorn/kg 185 pts/kg; yield 2010. (Figure 4): germination capacity 71%, rotten and decayed seed 29%, 1000 seed weight 4933 g, number of acorn/kg 203 pts/kg.
Based on study of acorn periodicity yielding and quality crops conclusions can be made: degree of crown defoliation significantly influences quantity of produced acorns, old forests produced the most acorns, seed production decreased with age. Number of seedlings shows us that the most quality acorns remains in crowns and its fells after commercial seed collecting are completed. In middle aged forest number of seedlings in double the quantity than other investigated stands, acorn maturation is longest, and acorn fells on ground later. Monitoring of dynamics and seed production quantity during 11 years, crop years occurs significantly every 2 to 3 years and they differ in quantity. During that period were 5 mast years. Abundance of yield represents productional potential of stands. In old stand abundant acorn crops is identified with average yield of 269 kg/ha or 114748 pts of acorn /ha. Seed production abundancy is far below what is considered as abundant, therefore significant effort is required for preserving acorns in crowns after maturing and felling on the ground.

Key words: pedunculate oak; acorn production; acorn quality; acorn-collecting traps method; stand production potential

    GRADEČKI, Marija    ŠL
    NOVAK-AGBABA, Sanja    ŠL
    LICHT, Robert    ŠL
    POSARIĆ, Darko    ŠL
Topić,V., L. Butorac, G. Jelić  UDK 630* 539 (Arbutus unedo L.) 182
Wood and Foliage Mass in Strawberry Tree (Arbutus unedo L.) Maquis on theArea of Vrgorac      
Summary: Stating of biomass in forest ecosystems and development of models for its quick estimation is an important part of investigation, especially on karst. During many years of research on research projects the authors have collected and partly published data about biomass for some important species on Mediterranean karst area of Croatia.
This paper presents the results of green wood and foliage mass measurement above soil level in maquis of strawberry tree (Arbutus unedoL.). Research was made and samples collected on permanent experimental plot on Vrgorac area. The plot has dimensions of 1 ha, the subplot number 15, which was excluded and on which measurements on vegetation was made and its basic structural data stated, has 100 m2(table 1). Canopy on subplot amounts to 69,61%, the medium height of sprout of strawberry tree is 1,61 m (maximal 2,30 m). Wood and foliage mass on experimental plot was measured separately for every bush as weight and volume, the independent estimation were the height of the bush, diameter of the crown and number of sprouts on the trunk. The weight of wood and leaf was measured in kg, the volume in m3, the height of the bush and diameter of bush crown in m. The volume of wood in research maquis, on the area of 100 m2, amounts to 0,095 m3, the volume of leaf 0,074 m3. The important part of the research also comprises the model for quick and reliable estimation of wood and leaf mass in these forest ecosystems. General lineal modelling was used for development of the model.
In table 3 it is evident that the height and wood volume is in strong correlation with number of sprouts on the trunk (r = 0,611) and bush height (r = 0,619) and in very strong correlation with crown diameter (r = 0,846). The weight and leaf volume are in strong correlation with bush height (r = 0,610), in very strong with number of sprouts on the trunk (r = 0,775) and crown diameter (r = 0,892). On the basis of number of sprouts on the trunk, bush height and diameter of the crown, as independent variables, the weight and wood and leaf volume of strawberry tree were estimated by univariate and multivariate regression analysis. In table 4 and figure 4 the regression models for estimation of weight and volume of wood and foliage of strawberry tree on experimental plot 15 are shown. By univariate regression analysis the significant dependance on weight and volume of wood and leaf with number of sprouts on the trunk, height of bush and crown diameter was stated. The results show that the number of sprouts explains 35,5% (ß = 0,611; p<0,0001), the height of the bush 36,5% (ß = 0,619; p<0,0001), the crown diameter 70,7% (ß = 0,846; p<0,0001) the variability of the weight and wood volume. The number of sprouts on the explains 59,2% (ß = 0,777; p<0,0001), the height of the bush 35,4% (ß = 0,610; p<0,0001) and crown diameter 79,0% (ß = 0,893; p<0,0001) of variability of leaf weight and volume. In figure 4, besides regression analysis of dependance of weight and volume of wood and leaf on number of sprouts on the trunk and diameter of the crown the equations of regression line beside the level of significance of 5% were given.
By multivariate regression analysis (table 4) the significal dependance of weight and tree volume and leaf with crown diameter was stated Td-(ß = 0,756; p<0,0001), Tl-(ß = 0,843; p<0,0001), while the significance for bush height was not stated Td-( ß = 0,142; p<0,233), Tl-( ß = 0,078; p<0,441).
The results of multivariate regression analysis show that the crown diameter and height of bush explain 71,1% of variability of weight and volume of wood (R2= 0,711) and 78,8% variability of weight and leaf volume (R2= 0,788).
All models can be applied for quick and reliable estimation of biomass of species (wood and leaf) in maquis of strawberry trees, especially with variables of crown diameter.

Key words: wood and leaf mass; maquis of strawberry tree; weight and wood volume; weight and foliage volume; crown diameter; number of sprouts on the trunk.

    TOPIĆ, Vlado      ŠL
    Butorac, Lukrecija
    JELIĆ, Goran    ŠL
Perić,S., M. Tijardović, A. Jazbec  UDK 630* 232:233 + 120 190
Results of Research on Douglas Fir Provenances in Ecologicaly Different Continenetal Parts of Croatia      
Summary: Establishment of forest cultures in Croatia begun around 1970s. Since then, share of cultures in Croatian forest fund varies while today it amounts to about 3 %. New scientific knowledge points out to justifiable reasons of further and enhanced establishment of Douglas fir cultures in Croatia (especially spontaneous increase of suitable areas for their establishment such as former agricultural land). This paper presents results of scientific Douglas fir research conducted in the scope of project “Management of conifer cultures”. Numerous trials which have been established during the last 40 years (in the scope of activities of Croatian forest institute) with the aim of determining the most suitable provenances for establishment of conifer cultures in Croatia have provided first results. According to those results Douglas fir showed best growth success among all investigated species.
Douglas fir is one of the most valuable and important specie for timber production in the world. Combination of high quality wood with high productivity places Douglas fir on the top of the world’s timber production. In the country of its natural distribution this specie is the object of numerous scientific publications, while the research on Douglas fir success in Europe was conducted mostly in the scope of culture establishment. Its natural distribution spreads in the west part of North America. This specie is successfully introduced in almost all areas of temperate region in the world (Europe, southern part of South America and Australia) and in New Zealand. Douglas fir cultures occupies immense areas in North America where this species is naturally distributed.
Douglas fir successfully adapts to broad range of site conditions, while provides high incomes and high quality products. It successfully grows in different climatic conditions, especially on deep and aerated soils, with pH 5–6, while on heavy soils with higher water content shows lower success. Although Douglas fir is the specie with deep root system, morphology of roots depends on soil properties. In the context of climate change Douglas fir seems to be very interesting commercial specie for Europe since it adapts easier to conditions of temperature increase and rainfall decrease during the vegetation period. Consequently, Douglas fir could be superior to Norway spruce which is currently most important economic specie in the Europe. Those characteristics, together with results of former research conducted on its success, makes Douglas fir suitable for establishment of new cultures on non-forest land in Croatia.
As a result of all above mentioned information, part of this research was focused on analysis of Douglas fir provenances success 40, 42 and 45 years after culture establishment on three different localities of continental part of Croatia. Research on Douglas fir growth success was conducted in the 40th year after trial establishment on locality Durgutovica (Forest administration Vinkovci, Vinkovci forest office, ,) in the 42nd year on Slatki Potok locality (Forest administration Bjelovar, Veliki Grđevac forest office), and in the 45th year on the locality Mikleuška (Forest administration Zagreb, Kutina forest office). Trials were established in randomized block design in four repetitions. Trials include 23 different provenances in total (on all investigated localities – presented in Table 1). 19 provenances originate from areas of its natural distribution, mainly from lower altitudes (6 from Oregon, 3 from British Columbia and 10 from Washington). Four provenances originate from Europe, two of whichare from Croatia (Rovinj and Skrad), one from Bulgaria (Šipka) and one from Denmark (Hvidilde). Statistical analysis which has been conducted for all measured parameters (DBH, height, volume) on all localities showed statistically significant difference between provenances in the case of provenances on localities Durgutovica and Slatki Potok, while there is no difference between provenances on Mikleuška locality (presented in Tables 3, 4 and 5 for volume). Descriptive statistics for all localities, provenances and parameters is presented in Table 2.
Provenance with the highest average value of all analyzed parameters on locality Durgutovica is Hvidilde from Denmark (39,4 cm DBH, 27,7 m height, 1,68 m3 volume). In the case of volume, there is no statistically significant differences of this provenance and all other provenances except Šipka (1,45 m3) from Bulgaria and Tenino (1,41 m3) from Washington. Based on this result, those three provenances can be highlighted as the best provenances regarding volume on locality Durgutovica. According to statistical analysis of all analyzed parameters (DBH, height, volume) the poorest success on locality Durgutovica showed provenances Salmon Arm from British Columbia (26,1 cm DBH, 20,7 m height, 0,64 m3 volume) and Skrad from Croatia (29,7 cm DBH, 22,0 height, 0,80 m3 volume).
Provenance Elma from Washington, and generally speaking all provenances from Washington and European provenances from Denmark and Bulgaria showed the best success on Slatki Potok locality. On this locality the lowest average value of volume shows provenance Shady Cove (0,32 m3) from Oregon, which statistically differs from all provenances except provenance Salmon Arm (0,33 m3) from British Columbia. Those two provenances are excluded as the worst on this locality according to all analyzed parameters. The lowest DBH values belong to provenances from British Columbia and Oregon. 95 % confidence intervals for DBH on this locality are presented on Figure 1.
For volume value on locality Mikleuška it is determined that there is no statistically significant difference among four existing provenances (Cortage Grove-Oregon; Centralia-Washington; Cascadia-Oregon and Ashland-Oregon). 95 % confidence intervals for volume on this locality are presented in Figure 2.
On the basis of presented results we conclude that provenances with the best success for all localities are those which originate from lower altitudes (0-300 m a. s. l.)of The State of Washington (Elma, Tenino) and Europe (Hvidilde from Denmark and Šipka from Bulgaria). As those provenances showed the best success in continental part of Croatia we recommend that they should be used for establishment of new cultures in Croatia.
High production and wood quality together with wide range of ecological conditions places Douglas fir on significant position for new forest culture establishment in Croatia. New scientific knowledge highlights its significance in the scope of climate changes where it is recognized as species of beneficial biological properties.
This project was conducted under auspices of “Hrvatske šume” Ltd., so we would like to use this opportunity to express our sincere thanks for financial help as well as to thank all employees of forest and administration offices for their immense help.

Key words: Douglas fir; forest cultures; success; provenance; Croatia.

    PERIĆ, Sanja      ŠL
    TIJARDOVIĆ, Martina    ŠL
    Jazbec, Anamarija
Novak Agbaba,S., N. Ćelepirović, M. Ćurković Perica  UDK 630* 442 202
Protection of Sweet Chestnut Stands      
Summary: In this paper the influence of care, cleaning and thinning on the health condition of chestnut, on the chestnut blight disease and various types of cancer formations are investigated. The aim of this work is the protection of chestnut trees and raising the quality of chestnut stands and trees and to determine how to manage with the chestnut stands to its preservation. For this purpose, the experimental plots were established in the Forest administration Sisak, in Forest office Hrvatska Kostajnica in Management Unit Šamarica I, department 91A. Experimental plot I was managed with strong thinning intensity: one to two chestnut trees were left on the stump. Experimental plot II was maneged with lowthinning intensity: three to five chestnut trees were left on the stump. Removed trees were irregular growth, infected with active cancer. The healthy tree and tree with healing superficial necroses were left. The size of experimental plots was 50 x 100 m. On experimental plots the health condition of trees, differengt types of cancer formations and diameter degree of trees were registered. The survey was carried out in 2010th year in the fall at the end of vegetation. In the Forest office Hrvatska Kostajnica in management unit Šmarica I in the compartment 92 a the samples of bark infected with cancer were collected and the fungus Cryphonectria parasiticawas isolated. Population structure of the fungus were analysed and 8 vegetative compatibility types were detected. The most frequent types were EU 2, EU 1, EU 12 and EU 11. Hypovirus was found in all white tested isolates. The collection of the white hypovirulent fungus ofCryphonectria parasiticastrains was established. The hypovirulent strains ofCryphonectria parasiticawill be used in further research for biological treatment of active cancers. The Experimental plot I with a stronger intensity of thinning,trees achieve larger diameters and a higher percentage of healthy trees and trees with healing cancer and smaller percentage of trees with active cancer. On the control plot, the diameter of the threes, the percentage of the healthy trees and trees with healing cancer were lower. but more trees with superficial necrosis The results indicate the need for continuing follow-up experiments and to establish a new experimental plots in order to protect the chestnut stands and increasing its quality.
Keywords: sweet chestnut, protection of chestnut stands, chestnut blight, Cryphonectria parasitica, management measures, health condition

    NOVAK-AGBABA, Sanja    ŠL
    Ćelepirović, Nevenka
    Ćurković Perica, Mirna  
Indir,K., V. Novotny  UDK 630* 55 : 565 211
Circular Sample Plot Size Impact on Structure Elements Estimation in Selected Pedunculate Oak Stands      
Summary: Data collecting in forest inventory in Croatia are carried out on a temporary sample plots (circles or strips). In this article, sample of 86 circular plots established in Repaš-Gabajeva Greda management unit (Fig. 1), Repaš forest office, Koprivnica regional forest office, is used to see how the basic structural elements (stem number – N, basal area – G and stand volume –V) are changing when the sample plot radius is decreasing. Research area is typical lowland pedunculate oak and hornbeam stand (Carpino betuli-Quercetum roboris (Anić 1959) Rauš 1969. Sample plots covered the whole management unit area and stands older than 40 years, from 3rd to 7th age class. Sample units were circular, with radius 15 to 30 m, bigger than in regular forest inventory (Table 1) which are usually 12,62 m and 18 m in radius.
All trees above 10 cm in dbh within circular plot were measured. Plot center was marked with iron bolt below ground level. Position of each tree is determined with distance and angle from plot center. Haglof caliper was used to measure two dbh of each tree. Total tree height was taken with Suunto hypsometer.
Data collected in a field, were entered to database created in Microsoft Access. For each plot, number of trees per hectare, basal area per hectare, and volume per hectare, were calculated, separately for tree species and total. These basic structure elements were calculated for different plot sizes, lower than taken in field. It has been done using database queries, thanks to recorded position of each tree. For a particular criteria (distance from plot center), only trees that are within required radius were selected. In 3rd and 4thage class, plot radius from 5 to 15 m, with 1 m step, is used to calculate structure elements (Table 2). In 5thage class, examined plot radius range was 15–25 m, and in 6thand 7thage class 20–30 m (Table 3).
Calculated elements were examined with simple statistical analyses in order to get variation coefficient (CV), and precision (SP). The results showed that in 3rd, 4thand 7thage class there is not enough sample plots to bring conclusions because variation coefficient values are high and precision is at poor level. (Fig. 3–8). In 5th and 6th age class for all examined plot radii, estimated precision of basal area and stand volume is better than 5 % (Fig.7, Fig.8), and variation coefficient is in range of 15,3–26,4 % (Fig. 4, Fig. 5). Stem number estimation shows precision of 5,3–6,0 % (Fig. 6).
In given research area and stand conditions, conclusions are:

– in 3rd, 4thand 7thage class variability in small amount of sample plots is too high to bring resolute conclusion

– regarding to variation coefficient and estimation precision values, there is no need to use sample plot radius greater than 15 m in 5thage class, and 20 m in 6thage class

- with more sample plots in 3rd, 4thand 7thage class, and use of lower sample plot sizes in 5thand 6thage class, optimal plot radius that gives reliable and precise stand structure elements estimation could be reached.

Key words: Pedunculate oak; sample plots; stand structure elements; estimation precision

    INDIR, Krunoslav    ŠL
    NOVOTNY, Vladimir    ŠL
Vuletić, D., S. Krajter, O. Vlainić  UDK 630* 907 + 907.2 222
Review of Local Residents and UsersAttitudes Towards Nonwood Forest Products and Services with Remarks on Obstacles and Possibilities for Improvement      
Summary: This paper presents results of research project “Defining of values and possibilities of use for non-wood forests’ products and services financed by Croatian forests ltd. and executed by Croatian Forest Research Institute in cooperation with Forest District Karlovac (2005–2010). Non-wood forests´ products were defined as group of forest fruits and mushrooms, and services as group of social forests’ services (recreation and landscape).
Method chosen for analysis and interpretation of results from two different investigations was triangulation (Denzin and Lincoln 1998 i 2003). First investigation was done with population of Peters´ mountain (2007–2008) using face-to-face interviews (table 4), and second using questionnaire send by mail to citizens of Karlovac (table 5) as users of forest services (2009–2010).This method allowed us to put results from different investigations into relation with aim to get better picture and understanding of investigated phenomenon. In addition the data on forest suitability for providing forest services were collected too. Those data were used for defining forest suitability for providing recreational and landscape services to users.
Results show high level of correlation between attitudes of two different groups of respondents, and significant recognition of importance of ecological, recreational and landscape forests´ services (figure 1). Another finding is that both groups of respondents very often and gladly visits forest, mostly for purpose of rest and recreation, but also for health reasons (table 7 and 9) (Vuletić et al 2009). During their visits to forest they often almost regularly collect forest fruits, and they recognized this activity as very important for them (table 8).
They are also equally satisfied with state of forests. However, the level of respondents’ satisfaction decreased with increased level of education. Contrary level of satisfaction is low when it is about state and maintenance of recreational infrastructure in forests. Especially they missed adopted infrastructure for disabled people. The forests´ suitability for providing recreational and landscape services is for almost whole area of Peters´ mountain excellent and very good (table 6) and we see this as a clear sign of huge potential for developing recreational activities and for use in marketing of whole recreational area. Also this could be used to facilitate private entrepreneurship development based on use of forests’ non-wood products for which the both groups of respondents recognized the potential. The local population expresses also interest to start private entrepreneurship where those which owned they forests were more interested in it. Peters´ mountain with the recreational center “Muljava” with numerous of visitors (table 1) presents huge potential for developing recreational activities based on collection of non-wood forests´ products which will motivate their visitors to prolong their stay in forests. The existing common interest for non-wood forest products and fruits should be used and connected through possibility to sell collected fruits to some of local collectors, which could boost the private entrepreneurship in these poorly developed areas with almost non additional investments.
Although, for getting the whole picture of investigated phenomenon additional research should be planned and executed giving the special attention to concrete visitors of forests and this recreational area and in second hand to private entrepreneurs to find out what are the critical factors which can initiate or foster those activities.

Key words: nonwood forest products and servised; landscape diversity; recreation; triangulation

    VULETIĆ, Dijana      ŠL
    KRAJTER, Silvija    ŠL
    VLAINIĆ, Oliver    ŠL
Vrbek, B., I. Pilaš  UDK 630* 114.4 + 232.4 230
Researches of Soil Changes in the Pinus and Robinia Forest on Đurđevački SandsArea      
Summary: In the area of Đurđevački pijesci (Northern Croatia), at the end of 19thct, forestation with the Scotch and Austrian pine has been carried out; later on it has been performed with the black Locust as well, the aim of which was to calm the active sands down and to stop the “Croatian desert” to spread, together with improving of the ecological life conditions.
After about 100 years, this work analyses the forest vegetation influence on some soil characteristics and crop productivity. The investigated vegetation spread in an area of forest community of Peduncled Oak and Common Hornbeam(Carpino betuli-Quercetum roboris, Anić 1956 ex. Rauš 1969). The average annual precipitation quantity is 950 mm; the average annual air temperature is 10,1 oC. The parent material of soils contains 78–80 % SiO2 and 2–4 % CaO + MgO. The most important results of these researches are:
On sand area in north Croatia (Đurđevački Pijesci) in the period of 90–110 years under the forest of Austrian pine, Scotch pine and Black Locust there has been formed – Rubic, Folic, Protic, Endogleyic, Haplic Arenosols (Dystric, Greyic, Novic, Transportic). From the mentioned research and soil data it can be concluded that the forest vegetation had a strong influence on a progressive direction of the soil evolution. The sands represent a very recent pedogenetic formation belonging mainly to the genetic-evolutionary stage of leached sirozem (grey desert soils) with a tendency of future development towards the initial Leptosol (Ranker).

Key words: Đurđevački pijesci; arenosol; forest vegetation; pedogenezis

    VRBEK, Boris      ŠL
    PILAŠ, Ivan      ŠL
Seletković,I., N. Potočić, M. Šango  UDK 630* 232.3 (Fagus sylvatica,Quercus robur) 239
Useability of Hungavit, a Preparation for FoliarApplication, for Enhancement of Quality of Common Beech (Fagus sylvatica L.) and Pedunculate Oak (Quercus robur L.) Seedlings in Nursery Production      
Summary: In this paper the results of two nursery experiments dealing with the influence of preparation for foliar application “Hungavit” on the growth and development of common beech and pedunculate oak bare-root seedlings are given. The experiments were set up as randomized blocks with three treatments and three repetitions. A generally positive influence of Hungavit on the development of seedlings was established. With beech, Hungavit had the greatest influence on the potassium, calcium and magnesium concentrations in leaves, biomass of leaves and stems and several important root properties, such as number of root tips.
The highest concentrations of nitrogen in beech leaves were present in B1 treatment (1% Hungavit). In oak leaves concentrations decrease with dose. Normal values in beech were reached only in B1, and in oak in all treatments. Phosphorus concentrations were highest in treatment 1 in both species, and all values correspond to normal range of values (Bergmann 1992 according to Fiedler and Hohne 1985). Potassium, calcium and magnesium concentrations increase with Hungavit dose (Table 2). The influence of Hungavit on height or radial increment of seedlings was not established.
Leaf and stem biomass of beech seedlings was increasing with dose, and for oak it was hihest in H1 treatment. An increase of lenght, surface area, volume and number of root tips with dose was recorded for beech seedlings (Table 5).
With pedunculate oak, the influence of Hungavit is less pronounced: Hungavit application had a positive influence on the potassium, calcium and magnesium concentrations in leaves and biomass of leaves and stems.

Key words: Hungavit; pedunculate oak; common beech; nursery; nutritional status; biomass; root

    SELETKOVIĆ, Ivan      ŠL
    POTOČIĆ, Nenad      ŠL
    ŠANGO, Mario    ŠL
Paladinić,E., D. Štimac, H. Marjanović, I. Balenović, M. Z. Ostrogović  UDK 630* 49 : 562 (Abies alba Mill.) 248
ProductionAspect of Silver Fir (Abies alba Mill.) Dieback on Example of a few Beech-fir Stands      
Summary: The research problem, raised by Croatian Forests Ltd., Forest Administration Delnice, is the frequent discrepancy in planned versus realised yields during selecting cutting in fir-beach forests. This discrepancy between planned and realised wood assortments structure and at the same time between revenues, is significant for fir-beach stands affected by fir trees dieback. The result is that performed sylvicultural activities in such disturbed stands, in order to get timber assortments, have questionable cost-effectiveness, and in some cases are fully unprofitable. The key point in process of calculating planned values according to timber assortments are so called “Assortment tables”, empirical models for estimation of timber assortments structure, which are definitely inappropriate for current climatic and disturbed stand conditions. Hence, the aim of this research is to study existing Assortment tables for fir, which are used by the Production department of Forest Administration branch Delnice, in order to satisfy criteria for sufficiently reliable planning in the production of timber assortments.
Material and methods. In order to ensure quality and uniformity of research from the be ginning, the detailed plan of field activities was designed and agreed for implementati on with Production department. On the research area in target Forest management un i ts, a few forest compartments were chosen for field data acquisition each year. In each of selected forest compartments it was required to collect data for around 100 marked fir tr ees, which were felled during selecting cutting. Diameter distribution of those hundred tr ees should represent fir diameter distribution of whole compartment. Each of those fir tr ees got measured diameter at breast height, total height, height of the first branch, and all bucked timber assortments. From those data we got volumes (per trees and per timber assortment). Ultimately, assortment structure data were collected from seven forest co mpartments. Each compartment has two dataset, one representing produced timber assortments (done by foresters) versus planned assortment structure (calculated using assortments tables).
Concerning research aim, two hypotheses (H1, H2) were constructed. H1 states: If planned and realised timber assortments production from forest compartment significantly affected by fir dieback is compared, than statistically significant differences between planned and realised values according to assortments classes will be confirmed. H2 states: If timber assortments production is compared according to three general health categories of fir stands, than statistically significant differences between same assortment classes will be confirmed. For testing H1, One-way ANOVA was used together with Test of Homogeneity of Variances. Analysed variables are veneer logs volume, sawlogs (1st, 2nd and 3rd class), pulp-wood and firewood, and volume of wood residues (recovered wood). Pulp-wood and firewood are in the same category, because only 14 pieces of firewood were measured in whole sample. Wood residue category refers to timber assortments thicker than 16 cm and left on forest floor because of its uselessness for technical purposes (damaged, decayed).
Statistical significance of differences between samples of planned and realised volume according to assortment classes was analysed. Testing homogeneity of variances between these two samples showed in most cases that variances of the same assortment classes’ volumes are not homogenous. Considering this findings, Independent-samples T test was used for analyzing H1. Analog to H1 testing, the same tests were used for H2 analyzing. Forest compartments which were compared represented two of three health categories of fir stands (stands of moderately damaged health condition were missing). Those two compared groups of data were unequal in size, one consisting of data acquired from 5 forest compartments, and another of data acquired from two forest compartments.
This research was partially extended with sampling of fallen fir trees to get a clue about insect and pest species which could be one of main factors causing fir dieback. So, in the 2008 woody samples collected from fallen trees in one forest compartment, were analysed in CFRI laboratory.
Research area. In wider context, research area represents fir-beach stands of Gorski Kotar region, and narrower area is determined by boundaries of Forest Administration Branch Delnice i.e. forest area affected by intensive fir trees dieback. The stands in focus represent main fir-beach forest community in Gorski Kotar, Abieti-Fagetum illyricum Ht. Research activities on field data acquisition were started in forest management unit “Brloško”. Data about forest compartments included in research are presented in Table 1.
Results of research and discussion. Firstly, the results of H1 are presented and discussed. Statistically significant differences between planned and realised volumes were confirmed for veneer assortment, for all forest compartments except one. The results were expected because five of seven compartments are considered as stands of significantly disturbed health condition, where possibility for production of high quality timber assortments from fir trees is minimal. Another fact considerably affects on differences between planned vs realised timber assortment structure is assortments tables, according to which each tree with dbh higher than lowest threshold for veneer class gets certain veneer volume from tree volume. Veneer volume participates in the whole sample of produced timber assortment volume with 0.59 %, and concerning forest compartments from 0.00 % to maximum 3.01 % (see Table 2).
T-test results for 1st class saw logs confirmed discrepancies between realised and planned quantities for all forest compartments except compartment no.15 in forest management unit “Brloško” (t value is 0.80). Volume of 1st class saw logs participates in the whole sample of produced timber assortment volume with 5.85 % to 35.95 %, concerning forest compartments. Different from previous, t-test for 2nd class saw logs confirmed discrepancies between realised and planned quantities for three forest compartments, two representing category of good health condition, and one category of worse health condition (table 3). Volume of 2nd class saw logs participates in the whole sample of produced timber assortment volume with 13.93 % to 31.28 %, concerning forest compartments. Testing volume of 3rd class saw logs confirmed discrepancies between realised and planned quantities for four forest compartments (two in category of good health condition, and two in category of worse health). This assortment class after pulp-wood and firewood has the highest share in whole sample volume of assortment classes. Volume of 3rd class saw logs participates in the whole sample of produced timber assortment volume with 16.29 % to 36.90 %, concerning forest compartments.
The most frequent timber assortment is pulp-wood and firewood category, leading by number of logs. This fact is in line with disturbed wood quality of standing fir trees which are in process of dieback or completely dead trees in the felling moment. Analysing discrepancies between realised and planned quantities for this assortment category, tests confirmed statistically significant difference for all forest compartments except one. Tested wood volume of the category participates in the whole sample of produced timber assortment volume with 6.38 % to 54.41 %.
Recovered wood (i.e. wood residue) assortment is problematic because of its technical inapplicability. This assortment category consisted of small number of pieces, and according to assortment tables each tree gets certain volume of the assortment (so called wood waste). This discrepancy is supported with T-test results confirming significant differences between realised and planned quantities for all forest compartments. Hence, further consideration of the recovered wood assortment was cancelled.
Regarding to obtained results, it can be concluded that H1 is accepted because statistically significant differences have been confirmed for majority of tested combinations. Testing H2 by ANOVA and T-test, for each assortment class were confirmed differences between assortment volume variances comparing two health categories of stands (table 4). Other words, the relationship between health categories of fir stands and realised assortment structure has been confirmed. Concerning this, in process of timber assortment production planning more attention on assortments tables should be done (carefully choosing and constructing new ones adapted for different health categories).
Conclusions. This project was aimed to give additional contribution in resolving discrepancy between planned and realised timber assortment production from fir-beech stands with different degree of fir trees dieback. The main reason for this discrepancy, especially in case of same health category stands, most probably lays on current assortments tables which were constructed in 90’is and updated a few times mostly on empirical basis. Another reason, but with considerably smaller influence on final production plan than assortment tables is inappropriate tariff selection.
Performed statistical tests confirmed significant differences between planned and realised timber assortment quantities in case of veneer. And such results are in strong correlation with worse health condition of the majority ofresearched forest compartments (except the ones in f.m.unit “Široka Draga”). Tests have been confirmed H1 on other timber assortments mostly for 1st and 3rd class of saw logs, pulp-wood and firewood category, and for 2nd class saw logs haven’t. Worse wood quality of fir trees from stands with significant fir dieback resulted in the statistically significant differences between planned and realised values of pulp-wood and firewood assortment volumes. Recovered wood category hasn’t been further analysed because of quite a small sample collected on the field.
Testing H2 on realised production data of the same timber assortment types between forest compartments belonging different health category, significant discrepancies in quantities of assortment volumes between two observed health categories have been confirmed.
Final recommendation or question to forest Management is “Would it be possible to adjust spatio-temporally the realisation of sanitary selecting cutting in fir-beach forests on yearly basis, in order to minimise timber production costs?”

Key words: health status category of stand; silver fir; dieback; forest woody assortments; planned production; realised production

    PALADINIĆ, Elvis    ŠL
    ŠTIMAC, Denis    ŠL
    Marjanović, Hrvoje
    BALENOVIĆ, Ivan    ŠL
    OSTROGOVIĆ, Maša Zorana    ŠL
Matošević,D., M. Pernek  UDK 630* 453 264
Alien and Invasive Insects in Croatian Forest Ecosystems and Estimate of their Damage      
Summary:Alien species are intentionaly or unintetionaly introduced species into new area. When an alien species succefully invades and impacts a new ecosystem it becomes an invasive species. Until today, 109 invasive insects on woody plants (57 from North America, 52 form Asia) have been introduced and established in forest ecosystems in Europe (MATTSON et al. 2007). Introduction and dispersal of new species is increasing from year to year due to globalization of trade and ever increasing tourist traffic between continents. The aim of this research was to identify most important alien and invasive insect species in Croatian forests and give an estimate od their damage and prognosis of their future spread.
The research has lasted for 5 years (2006 to 2010) and potential host plants in continental, submediterranean and mediterranean parts of Croatia were researched. For each invasive species found a prognosis for their future spread and damages is given according to their biology, ecology, researches on natural enemies and data from the literature.
Seven (7) insects species from the orders Lepidoptera, Hymenoptera, Diptera and Hemiptera were found and they can be cosidered as alien or invasive species in Croatian forest ecosystems (Table 1). For each insect species a host plant, locality where the insect was found and prognosis of damage on the scale from 1 to 4 (1-no influence on host plant, 4-serious forest pest) is given.
Parectopa robiniella, Phyllonorycter robiniella, Phyllonorycter issiki, Obolodiplosis robiniae, Leptoglossus occidentalis, Metcalfa pruinosa, Dryocosmus kuriphilusare alien or invasive insects established in Croatian forests. Introduction and spread of these species and their intensity of occurence has been very similar to the same pattern of spread and occurence in other Euro-paean countries. Several other invasive species on woody ornamental plants in urban areas have also been recorded in Croatia: Phyllonorycter leucographella, Dasineura gleditchiae,Argyresthia thuiella, Cameraria ohridella, Anoplophora chinensis.
Knowledge on insect origin, biology, ecology, pathways of introduction and spreading are very important for providing pest risk analysis and making relevant prognosis of dangers that a new pest is posing for forest ecosystems.

Key words: Parectopa robiniella; Phyllonorycter robiniella; Phyllonorycter issiki; Obolodiplosis robiniae; Leptoglossus occidentalis; Metcalfa pruinosa; Dryocosmus kuriphilus; amage

    MATOŠEVIĆ, Dinka      ŠL
    PERNEK, Milan      ŠL
Benko,M., I. Balenović  UDK 630* 587 272
Past, Present and Future of Application of Remote Sensing Methods in Croatian Forest Inventory      
Summary: Making correct decision in forest management is based on the quality of the collected information. Collection information from forests is the main task of the forest inventory. Due to the rapid development of technology, in the second half of the 20th century, there have been major changes in the way of data collection, particularly in developed countries. In addition to conventional terrestrial methods of data collection, data on forests is increasingly being collected with remote sensing methods. Using remote sensing methods leads to reducing the scope of the fieldwork, and opens the possibility of saving time and money.
In this paper was given the review of previous research and results of application of remote sensing methods in Croatian forest inventory.
Previous researches presented in this paper will give insight into the current status and role of remote sensing in Croatian forest inventory, and along with some new findings may serve as guidelines for future research and application of new methods of remote sensing in forest inventory.
Various researches about applicability of remote sensing methods in forest inventory operations, primarily on aerial photographs and more recently on satellite images, were conducted in Croatia in the last 30 and more years.
In all previous studies of forest damage assessments with photointerpretation on CIR aerial photographs it was proved that this method is to be equally in comparison with terrestrial methods regarding to accuracy, and much more efficient regarding to achieved speed and objectivity. Methodology suitable for operational use in inventory of forest damage was made. Periodic inventories of forest health with using remote sensing methods enable easy monitoring of changes of forest between two inventories, identification of new foci of dying trees or other damage, which is especially important in today’s changed and altered environmental conditions.
Forest management inventory requires information of greater accuracy. Therefore, aerial photographs of higher spatial resolution have more important applications in relation to satellite imagery in forest management inventory. Some researches of using aerial photographs for photogrammetric measurements of stands parameters shown in this paper gave good results.
Despite the above, the application of remote sensing methods in practical forest inventory has not been sufficiently utilized. Development of digital photogrammetry and ‘new’ remote sensing methods and systems such as lidar, and improving existing ones, increasing the possibilities and scope of remote sensing methods. Therefore is necessary to continuously monitor the latest developments and explore new additional possibility of their application in forest inventory.

Key words: remote sensing; forest inventory; aerial photographs; satellite imagery; digital photogrammetry; LiDAR

    BENKO, Miroslav    ŠL
    BALENOVIĆ, Ivan    ŠL
Novotny,V., I. Balenović, N. Medenjak, D. Štorga, D. Pošta  UDK 630* 569 282
Research on Structure of older and old Common Beech Stands in Management Unit “Đurđevačka Bilogora”      
Summary: Common beech (Fagus sylvaticaL) is the most videly distributed tree species in Croatia. Because of its physiological and ecological characteristics (high shade tolerance, ability to grow on a broad range of soil types, topographic positions, and climate conditions) common beech in Croatia forms different stands, from pure to mixed stands with different tree species, and with different structural characteristics. Characteristics of beech to oncoming in a wide range of different ecological and management conditions, and to creates stands of different structural characteristics, causes an increasing deviation of the structural elements values of managed stands in compare with values of the same stuctural elements that are tabulated in yield tables. Therefore there is need for investigation of structure of beech stands and applicability of yield tables at the local level for common beech and the other species that form beech stands.
The aim of this work is to research the basic structural elements of the managed beech stands and to compare them to the tabulated values in growth-yield tables, by local authors.
Field measurements were conducted on 449 circular plots located in 18 compartment in IV and V age classes in management unit Đurđevačka Bilogora. Intensity of sampling was 5% of a total area of selected compartments.
As expected, the results in this research show deviations in compare to tabulated values in yield tables, by local authors. Results show the complexity of problems in management with beech stands and need for local level approach in order to improve the distribution of age structure, product quality and sustainability of revenue on both local and global level, considering the purpose, method and management type of beech stands.

Key words: common beech; stand structure; yield tables; age structure; suistainability of revenue

    NOVOTNY, Vladimir    ŠL
    BALENOVIĆ, Ivan    ŠL
    Medenjak, Nikolina
    ŠTORGA, Dalibor      ŠL
    POŠTA, Damir    ŠL