|A WORD FROM THE EDITOR-IN-CHIEF|
|FORESTS MANAGED ON CLOSE-TO-NATURE PRINCIPLES ARE MUCH MORE USEFUL THAN VIRGIN FORESTS|
|At the Assembly of the Academy of Forestry Sciences held in December 2008 it was concluded that the majority of the forests in Croatia should be managed according to close-to-nature silviculture, an approach staunchly advocated by the Zagreb School of Silviculture. Such an approach encourages the natural composition of a forest accompanied by sustainable management, high quality of wood material and high productive potential. Carbon is sequestered, oxygen is released and CO2 quantities in the atmosphere are reduced in the process of photosynthesis. Since carbon dioxide is one of the most represented greenhouse gasses, a forest mitigates global warming by reducing its concentrations. This is currently considered one of the most important forest functions.
A virgin forest consists of five developmental stages: regeneration, the initial stage, the optimal stage and the stage of ageing and decomposition. In contrast, a naturally managed forest consists of the first three stages of a virgin forest: regeneration, the initial stage and the optimal stage. During its lifetime, carbon assimilation and sequestration play a major role, whereas during ageing and decomposition in a virgin forest assimilation decreases and finally stops completely. Since these two stages account for over half of a virgin forest lifetime, this forest is inefficient in the sense of carbon sequestration. Moreover, its anti-erosion and hydrological functions are also reduced.
The official policy of nature protection in Croatia advocates the maintenance of virgin forests. In contrast, the forestry science supports the principle of converting selected areas with the most important forest communities into secondary virgin forests for further study, and applying nature-based management in all forests.
Biological diversity displayed by a virgin forest in the developmental stages of ageing and decomposition is reflected in a large number of insect and fungi species in dead wood. This is achieved by leaving sufficient quantities of dead wood in a forest according to the FSC certification.
Professor Emeritus Branimir Prpić, PhD
PRPIĆ, Branimir ŠL
|ORIGINAL SCIENTIFIC PAPERS|
|Topić, V., L. Butorac, G. Jelić||UDK 630* 222 + 539 Arbutus unedo L. (001)||5|
|Biomass in Strawberry Tree Coppice Forests (Arbutus unedo L.) on Island Brač|
|Summary: The authors have collected and partly published the data about biomass for some important species on the Mediterranean karst area of Croatia during their research on projects. In this paper the data for strawberry tree (Arbutus unedo L.), whith together wit holm oak (Quercus ilex L.), laurestine (Viburnum tinus L.), crack phyllirea (Phillyrea latifolia L.), white heath (Erica arborea L.) and other maquis elements are published, which are found in Mediterranean littoral vegetation area of forest vegetation of holm oak (Quercion ilicis). This vegetation is spread from Istra to the Albanian border, especially on the middle and south Dalmatian islands: Brač, Korčula, Mljet, Lokrum and others. The vegetation develops in the form of closed maquis, rarely small forest (coppice). It grows till 10 m high and has a strong sprout strenght. It is completely adapted to ecologic situation of Adriatic forest, to draught, salt and cold, if it does not last long. Its fruit is edible and is used for making jam, spirit or liquer. It is also important as decorative plant in horticulture. It is especially nice in autumn, when the flowers and fruit are on the same branch. Research on strawberry coppice trees are done on experimental plots in Gornji Humac on the northeast part of the island Brač, dominated by unmixed and mixed evergreen oak forests. The plots have an area of 1 ha, the subplots 19 and 20, 25 m2 (table 1). The canopy on subplots amounts to 84,79 % (subplots 19), to 98,41 % (subplots 20), the medium height of sprout of strawberry tree is 3,60, that is 4,01 m (maximum 4,50 m). Biomass of wood and foliage on experimental plots was measured separately for every sprout as weight and volume, the independable estimatiors were the diameter od sprout on the height of 50 and 130 cm above ground, height of sprout and diameter of crown of the sprout. The weight of wood and leaves were measured in kg, volume in m3, diameter of sprout in cm, height of sprout and diameter of crown in m. Wood volume in coppice forests, on the area of 25 m2, varies from 0,276 to 0,405 m3, the leaf volume from 0,044 to 0,066 m3. The volume depends on the degradation stadium of coppice, that is on the dimension of species they consist of, their number on the unit of area, the way of grouping and the stand. The important part of the research is the model for quick and reliable estimation of biomass is forest ecosystems. General linear modelling is used for the development of the model. The research results showed that the wood and foliage volume in strawberry tree coppice is in strong, very strong and extremely strong linear dependance on the diameter of sprout, height of sprout and crown diameter of sprout. The correlation coefficients are between 0,599 and 0,961. The greatest correlation ceofficient has the relation of wood weight and sprout diameter at 50 cm height above ground level (r = 0,961). By univariate regression analyisis biomass above soil level in coppice strawberry trees can at best be estimated on the basis of sprout diameter, although the other independable variables also explain this regression model (table 4, figure 1). Diameter of sprout at 50 cm above ground explains 92,3 % of variability of wood weight, 72,6 % of leaf weight, while the crown diameter of the sprout explain 76,7 % of variability of wood weight and 75,9 % of weight and leaf volume. Multivariate regression models do not give much better results than univariate, especially at sprout diameter, as the best independable estimator, where values are equal. The diameter of sprout, its height and crown diameter of the sprout explain 87,9 % of variability of wood weight, 76,9 % of weight and leaf volume. Diameter of the sprout explains best this regression model for weight and wood volume, by weight and leaf volume of the crown diameter (table 5). All models can be used for quick and reliable estimation of biomass of each unit (wood and leaf) in strawberry tree coppice, especially with variable of sprout diameter.
Key words: biomass; crown diameter of the sprout; height of sprout; sprout diameter; strawberry tree coppice; weight and foliage volume; weight and volume of wood
TOPIĆ, Vlado ŠL
JELIĆ, Goran ŠL
|Prka, M., T. Poršinsky||UDK 630* 525 + 526 (001)||15|
|Structure Comparison of Technical Roundwood in Even-Aged Beech Cutblocks by Assortment Tables with Application of Standards HRN (1995) and HRN EN 1316-1:1999|
|Summary: This paper deals with research and comparison of technical roundwood structure in assortment tables compiled in accordance with the requirements of the Croatian standards for forest harvesting products of 1995 and the Croatian Standard Hardwood round wood - Qualitative classification - Part 1: Oak and Beech HRN EN 1316-1:1999. The research was carried out in the Management Unit "Bjelovarska Bilogora", Forest Office Bjelovar, Forest Administration Bjelovar. All investigated compartments pertain to ecological management type II-D-11 and management class BEECH with a 100-year rotation. The age of the investigated cutblocks ranged between 59 and 91 with thinning, between 94 and 110 with preparatory cut, between 100 and 112 with seed cut and between 98 and 114 with final cut. The group of sample trees was formed by random selection of approximately 10% of marked trees. The sample for compiling assortment tables in accordance with the requirements of the Croatian standards for forest harvesting products of 1995 involved 3001 sample trees (table 1), and assortment tables were compiled in accordance with the requirements of the Croatian standard HRN EN 1316-1:1999 based on 3082 sample trees (table 2). Share tables of wood assortments determined in accordance with these two standards were developed, for various reasons, separately for thinnings and preparatory felling, and separately for seeding and final felling. By processing sample trees in accordance with the requirements of the Croatian Standards for Forest Harvesting Products of 1995, 10,098 pieces of technical roundwood were obtained, whose total volume was 4,337 m3 (without bark). In accordance with the requirements of this Standard, total processed and classified net volume of all sample trees was 7,469 m3. By bucking sample trees in accordance with the requirements of the Croatian Standard Hardwood round wood - Qualitative classification - Part 1: Oak and Beech HRN EN 1316-1:1999, 13,507 pieces of technical roundwood were obtained, whose total volume was 6,010 m3 (without bark), and in accordance with the requirements of this Standard, the net volume of all sample trees was 8,931 m3. Due to substantial differences, structural comparison of technical roundwood classified in accordance with the requirements of these two standards is more simple and adequate for wood assortments of the best quality, veneer logs - A quality class (Fig. 1) and assortments of the lowest quality class, 3rd class sawlogs - D quality class (Fig. 4). The comparison is much more difficult with other quality classes of technical roundwood, logs for rotary cutting - 1st quality class sawlogs - B quality class (Fig. 2), 2nd class sawlogs - C quality class (Fig. 3), due to even more significant differences between standard requirements with respect to dimensions, range of timber defects, and number of quality classes. Differences between the Croatian standards for forest harvesting products (1995), still applied in Croatian forestry and international standards Hardwood round wood - Qualitative classification - Part 1: Oak and Beech EN 1316-1:1999 are numerous and significant. Differences are related to the number of quality class, prescribed minimum dimensions, range of roundwood defects along with way of measurement of technical roundwood and they reflect to different share of wood assortments (quality classes) determined in accordance with the requirements of individual standards. However, the key difference between these two standards lies in the fact that according to the "old" Croatian standards technical roundwood was classified by purpose, and according to the "new" Croatian standards technical roundwood is classified by quality, therefore avoiding to define its future purpose. Consequently, the comparison of percentage shares of wood assortments in the assortment tables is difficult, and defining unambiguous conclusions (except for assortments of technical roundwood of the highest and lowest quality) is questionable. Differences in contents between international standards and standards currently in use in Croatian forestry shall necessarily bring operational changes in bucking, scaling, classifying and marketing of forest products. Operational changes (partly conditioned by the acceptance of international laws and regulations) shall also be accompanied by certain changes in relationships within the forestry sector. Key words: assortment tables, Croatian standards of forest harvesting products 1995, Croatian Standard HRN EN 1316-1:1999, even-aged beech stands
PRKA, Marinko ŠL
PORŠINSKY, Tomislav ŠL
|Zečić, Ž., I. Stankić, D. Vusić, A. Bosner, D. Jakšić||UDK 630* 48 + 737 (001)||27|
|Volume utilization and value of timber assortmets of dried silver fir (Abies alba Mill.) trees|
|Summary: Silver fir (Abies alba Mill.) is naturally distributed in mountainous regions of central, southern and parts of western Europe (Figure 1). Ecologically, commercially and traditionally, silver fir is the most important Croatian conifer species, participating in the total conifer growing stock with about 35 % (Prpić and Seletković 2001). It occurs in selection forests, which represent an important ecological stronghold of the most forested region in the Republic of Croatia. The stand´s health status is assessed by monitoring the crown condition of individual trees. Dobbertin and Brang (2001) showed that mortality rates increase exponentially with increasing defoliation. Crown damage can be monitored indirectly and directly, but neither of these methods is completely objective (Redfern and Boswell 2004). The health status of forests in Europe is monitored on an annual level within the International Cooperative Programme on Assessment and Monitoring of Air Pollution Effects on Forests, ICP FORESTS. The programme was launched in 1985, and the Republic of Croatia joined in 1992. Monitoring is repeated in permanent plots by indirect (visual) assessment of crown defoliation of freely grown trees.
According to the assessment of forest condition in Croatia (ICP FORESTS) for the year 1999, undamaged fir trees accounted for only 14.3 %, whereas severely damaged trees accounted for as much as 63.8 %. Severe damage denotes crown needle loss ranging from 26 % to 99 % (Potočić and Seletković 2000). Particularly high participation of damaged fir trees of 81.6 % was recorded in Gorski Kotar in 1999, while only 3.8 % were healthy fir trees. The results of field research suggest that the portion of damaged fir trees is constantly increasing. Thus, as much as 88.4 % of severely damaged trees were recorded in 2004 (Vrbek et al. 2008). The value of wood assortments of dead trees from salvage cuts is lower compared to those obtained from regular silvicultural treatments in healthy selection stands. The goal of this research is to analyze the quantity, quality and value of wood volume obtained from salvage cuts of silver fir in a selection forest.
The research was conducted in the area of Gomirje forest administration within the management unit of "Potočine - Crna Kosa". The management unit extends over northern and north-eastern slopes of Mt. Velika Kapela at altitudes between 339 and 1,200 m. The compartment covers an area of 36.00 ha. The management class is a managed forest of silver fir and common beech with a total growing stock of 339 m?/ha. The growing stock of fir is 112 m?/ha. There are 304 trees per hectare, of which 157 are silver firs. To investigate fir trees during salvage cuts, breast diameters and heights were measured on every blazed tree and crown damage was directly assessed using the ICP FORESTS methodology. Trees marked for cutting were divided into two classes (degrees) of crown damage ("3b" and "4"). Crown damage for class "3b" ranges between 81 % and 99 %, while class "4" represents completely dry trees (Figure 3). The volume of each marked tree was calculated according to the Schumacher-Hall expression.
Values of wood and timber assortments change in accordance with changes in the society, on the market and in economic relations, and in accordance with the application of new technologies and impacts of other factors (Rebula 1996). Value analysis of the obtained wood volume is made by determining the price of every single timber assortment. The price of every single piece of roundwood corresponds to the valid pricelist of the main forest products. The pricelist is used to calculate the price of roundwood from forests owned by the Republic of Croatia during the sale of standing trees ("on the stump") to contractual buyers. Value coefficients were established in accordance with mutual relations of price classes in relation to the most represented price class, which was taken as 1.00. The results were expressed by the relative value ratio of timber assortments produced from trees in crown damage classes "3b" and "4".
Figure 3 shows distribution of dead silver fir trees in compartment 7b with regard to crown damage degree. Diameter classes range from 17.5 cm to 77.5 cm. The lowest number of trees, i.e. only one tree, was in the largest diameter class, while the majority of the trees were in the diameter class of 47.5 cm. A total of 200 trees with average breast diameter of 48 cm and average height of 29.4 m were marked and processed. A comparison of the total marked volume determined with the Schumacher-Hall form and the volume taken from the mentioned tables is given in Figure 5. The comparison was made on the basis of individual and total tree volume. According to Šurić, the total volume of marked trees was 491.93 m?, according to Schuberg it was 570.32 m?, and according to Schumaher-Hall it was 570.95 m?. Statistically significant differences (for p<0.05) were found in Šurić - Schuberg and Šurić - Schumacher - Hall relations, whereas insignificant difference was found in the comparison of volume of Schuberg - Schumacher-Hall.
The utilization percentage of wood volume is determined as the ratio of the produced wood volume and the volume of large wood over bark according to Schumacher-Hall (Table 2). In the sample, the utilization percentage ranged from 35.79 % to 87.10 % with an average of 71.97 %, or 73.54 % (Median). Wood waste amounted to 28.03 % (26.46 %) on average. In the "3b" damage class the average breast diameter was 53 cm and height was 31 metre. Overall marked volume was 157.31 m?, the volume of processed wood over bark was 137.07 m?, and that under bark was 120.42 m?. The average percentage participation of bark was 12.69% and was lower by 0.6 % than that in the "4" damage class. With regard to the net structure of 116.54 m? of roundwood, technical roundwood accounted for 77.13 m? (66.18 %), and pulpwood for 39.41 m? (33.82 %). Within overall utilization, 49.03 % related to technical roundwood and 25.05 % to pulpwood. With regard to the quality of felled trees, only logs in class I, II and III were produced, while the remaining volume related to pulpwood. In the structure of produced wood assortments, class I accounted for 19.85 %, class II for 43.78 %, and class III for 36.37 %. Of the total number in the sample, 156 trees were in the crown damage class "4". These trees had an average breast diameter of 46 cm and a height of 29 m. The total volume of marked trees was 413.64 m?. The volume of processed wood over bark was 356.60 m? and volume under bark was 312.56 m?, which shows that bark participates with 13.31% in the total wood volume. A quantity of 302.51 m? of wood assortments was produced, of which technical roundwood accounted for 114.01 m? and pulpwood for 188.51 m?. The percentage share of wood waste was 26.86 %. Overall utilization was lower than in class "3b" and amounted to 73.14 %. Within total utilization, 27.56 % related to technical roundwood and 45.57 to stacked wood. In terms of structure, technical roundwood accounted for only 37.69 % and pulpwood for 62.31 % of the net volume. Only logs in class I, II and III were produced. In the structure of produced wood assortments, only 5.02 % related to class I, 30.39 % to class II and as much as 64.59 % to class III.
Monetary value of trees is determined on the basis of volume of a particular diameter class and the price of principal forest products. The price of forest assortments made from standing trees ("stump price") was used to calculate monetary value of wood volume. According to the pricelist, monetary value of assortments was divided into three price classes based on the mean saw log diameter. The largest number of assortments was in the price class of pulpwood, for which an index of 1.00 was determined. Value indices given in Table 3 were established on the basis of the price ratio of other price classes and the mentioned one. Multiplying the price class index with assortment volume resulted in the assortment value index. The sum of all assortment value indices of individual trees is the relative value of the produced wood volume, i.e. relative tree value. Stem value rises with an increase in breast diameter. The value of damaged trees (Figure 7) in crown damage class "3b" is lower by more than 20 %, and the value of trees in class "4" is lower by more than 35 % in relation to the value of undamaged trees from regular selection cuts. Value increases per wood volume unit (Figure 8) in accordance with an increase in tree breast diameter. The reason is the absence of certain quality classes in the thinnest trees and division of monetary value according to the prescribed assortment diameter. The relative value of wood volume unit in crown damage class "3b" is lower by 10 % to 30 % than the value unit of undamaged trees. In crown damage class "4", the values of volume unit are lower by 30 % to 45 % in relation to undamaged trees.
Key words: silver fir; dead tree; utilization; roundwood; timber value
ZEČIĆ, Željko ŠL
STANKIĆ, Igor ŠL
VUSIĆ, Dinko ŠL
|Horvat, Gabrijel||UDK 630* 689 (001)||39|
|Improvement of Forestry Office Business Operation by Developing Basic Managing Functions|
|Summary: The analysis of business operation of forestry office, as the basic and fundamental organization unit in the Republic of Croatia, was done on the model of Ludbreg forestry office that lies within Forestry Head Office, Koprivnica Branch. In the process of analysis, the forestry office was presented through the survey of its complete organizational structure as well as its business operation and legislative regulations of Croatian forestry. In the research all the functions of forestry were analysed, such as productivity function, the function of protection and preservation of forests as well as the function of public education. The following methods were applied in the process of analysing ana evaluating: - SWOT analysis Based on SWOT analysis results, the fundamental strength lies within the qualified and motivated human resources supported by stable financing. Most of the factors of weaknesses within are the result of and are connnected to higher-ranked organizational system containing oversized hierarchy of decision making - There are possibilities to decrease the existing suborganizations of the main managing functions without destroying the basic principles of the organization and bussines protocols, as well as the possibility of developing new operations together with strengthening the public role of Forestry. - Poll Poll was made on the sample of 50 respondents from the various institutions, organizations or societies in the local area, such as local government, eductional institutions, and citizen´s associations. It included respondents selected by gender, degree of education and the fact whether they owned the private forests or not. The aim of the poll was to establish the role of forester´s work in the local area. The result of the poll showed that there is a serious interest in the well beeing and prosperity of the forests and environment among the public.The role and importance of the forester is regarded by the public quite high and this profession is considered to be important, ranked immediately after a doctor and a teacher, and before a vet and a lawyer. A full confidence regarding the management of forests is given to forestry profession. - Analysis of basic management functions Planning - within the sphere of planning it is suggested to include forestries into the decission making on the strategic level through the possibilities of widening the range of activities (ore and mineral resources, drinking water, plantations, transplanting and similar activities). It can be achieved by including forestry personnel into the working groups, ad hoc groups or teams especially when the development and application of local norms is the issue.
Organization - an approach to organize forestries into the profit centres with liberal organization scheme is suggested, as well as more modern forms of organization (project organization, Free Form Design). Managing the human resources - to define and enable for the qualified personnel the conditions of professional development and improvement applying the principle of permanent and whole life education. Leadership - team effort should be emphasized, supported and followed by stimulating bonuses as a reward. Control - the function of natural and financial control should be implemented by means of correct and timely system of information applying the systems and norms of quality control (such as ISO standard). On the basis of these researches and analysis the following general conclusions in connection with the improvement of forestry office business operation, were drawn:
1. the improvement of forestry office business operation is welcome, necessary, and inevitable in the light of further development of management functions within the frame of contemporary management concepts as well as constantly changable circumstances of business operation and conditions of environment and millieu;
2. business operation improvement is of the utmost importance as the operative support in the forthcoming restructuring of the firm;
3. business operation improvement must be supported by human resources whose qualifications, further stimulated by organizational and motivational means, play the crucial role in the forthcoming breakthrough;
4. the improvement of business operation mostly entails transformation of the managing functions in order to achieve better adjustment to the targets of modern multifunctional forestry as stated in the conditions of approved FSC certificate, which tends to be the mode of socially responsible forestry managing; as well as it entails the adjustment ond acquirement of the quality control norms (ISO 9000:2001; ISO 14000);
5. each improvement of forestry office business operation should proceed from location and position of the basic unit within the business operating system where the basic public and commercial activities of forestry department have been performed;
6. evaluation of possible contributions in the improvement of each and every management function should comprise the best examples of its realization in everyday practice within the comparative fields of activities constantly bearing in mind Croatian orientation for the concept of integral and multipurpose managing of forests and forestry resources;
7. improvement of business operation must equally refer to the commercial aspect of forestry office operation, as well as to its public educational function within the given environment so that it can motivate and inform this public about the importance of protection and preservation of forests in order to win it over and convince it that it is essential to have expert and responsible forestry management by competent forestry science and practice.
HORVAT, Gabrijel ŠL
|Dakskobler, Igor||UDK 630* 188||53|
|Phytocoenological Research in Forest Ecosystems at the Beginning of the 21st Century|
|Summary: Phytocoenology (phytosociology) studies interactions between plant communities. It researches the dependence of plants on the living and non-living environment (climate, parent material, mineral soil composition). It provides explanation for the selective manner in which nature operates, which enables plant communities adapted to specific sites to form from the surviving tree, scrub and other plant species; it gives an overview of these communities and their changes over time. The article gives an account of a comprehensive historical development of phytocoenology in Central Europe and a description of certain issues in the contemporary phytocoenological study of forest ecosystems with special regard to Slovenia and Croatia.
Phytocoenology developed in the 19th century when botanists did not only study individual plants, but also how entire vegetation changes within a landscape. The focus of their attention became plant formations or plant communities in relation to their environment. In the southeastern European region, phytogeographical (geobotanical) or vegetation studies in the second part of the 19th and at the beginning of the 20th century were published by F. Krašan, G. Beck and L. Adamović, for example. An important milestone was the Botanical Congress in Brussels (1910), where the concept of association was defined. This resulted in a fast development of the discipline, but different methods were developed in different parts of the world, and attention was paid to different issues. The most widespread, also in Slovenia and Croatia, was the Central-European (Braun-Blanquet, Zürich-Montpellier) method. Among other things, the pioneers of phytocoenological research in Slovenia (G. Tomažič, M. Wraber, and V. Tregubov) and Croatia (I. Horvat, S. Horvatić) conducted also thorough research of forest communities. In this respect, Horvat´s Biljnosociološka iztraživanja šuma u Hrvatskoj (Horvat 1938) is a pioneer work. In Slovenia and Croatia, phytocoenology established itself in forestry practice only after the Second World War. Soon after the end of the war two Horvat´s books, Nauka o biljnim zajednicama (1949) and Šumske zajednice Jugoslavije (1950), were published. Professors Dušan Mlinšek and Milan Anić deserve a lot of credit for the promotion of phytocoenology in the forestry of Slovenia and Croatia because they emphasised the significance of the knowledge and consideration of sites in contemporary silviculture. The result of a very fruitful cooperation of phytocoenologists in the then Yugoslavia and more widely, within the Eastern Alpine and Dinaric Society for Vegetation Ecology in the 1970s and 1980s, was also a map of natural potential vegetation of Yugoslavia in the scale of 1:1.000.000 (B. Jovanović et al. 1986) and Prodromus phytocoenosum Jugoslaviae (Zupančič et al. 1986). The work of the time was incorporated also into the Map of Natural Vegetation of Europe in the scale of 1:2500000 (Bohn et al. 2000).
Development of fast and more advanced personal computers in the 1980 s, which paved a way for relatively simple massive utilisation of mathematical methods (above all multivariate statistics) in comparisons of phytocoenological relevés and their grouping by environmental factors, brought about a significant turnaround in vegetation research conducted according to the Central-European and other methods. One of the first widely used software of this kind was TWINSPAN (Hill 1979). Later on other program packages, such as MULVA (Wildi & Orloci 1996), SYN-TAX (Podani 2001), JUICE (Tichy 2002), CANOCO (Ter Braak & Šmilaure 2002), PC-ORD (McCune & Mefford 2006), etc. were applied as well. In this respect, a problematic issue in the Central-European method is the subjective selection of relevés and subjective evaluation of cover or abundance of species with ordinal values (e.g. r, +, 1, 2, 3, 4, 5). There have been discussions among experts on the correct procedures for numeric processing of ordinal input data. Some, e.g. Podani (2005), believe that only ordinal classification and non-metric ordination methods are suitable for such data. Others disagree. A similar problem exists with the statistical analysis of data acquired using non-random (subjective) sampling, such as are also our relevés. Experts published their pro et contra views on when and to what extent such analysis is appropriate in the journal Folia geobotanica (Herben & Chytrý 2007). Despite the above concerns it is still true that the Central-European method allows a relatively fast, simple and inexpensive way of acquiring useful data on vegetation and its connections with the environment. Databases of vegetation relevés (e.g. TURBOVEG - Hennekens & Schaminée 2001) already keep large amounts of historic, several decades and even half a century old relevés that were made with subjective plot selection. Disregarding these relevés on account of their statistically problematic (subjective and non-random) origin would mean discarding very valuable ecological data. Ecologists therefore use these data to their advantage, but with regard to their limitations. These data are used also in contemporary overviews of vegetation of large regions (e.g. in Willner & Grabherr 2007). Using and processing large quantities of relevés has changed the views of the basic unit of the syntaxonomic system - association - in many ways, and has affected the way we see the concept of character and differential species (comp. Willner 2006). When selecting diagnostic species authors apply different computing procedures. A large number of relevés enable a relatively objective calculation of fidelity of species to certain syntaxa and their diagnostic value (e.g. with phi-coefficient - Tichý & Chytrý 2006). As a rule, in formalized classification the number of syntaxonomic units of a vegetation formation (e.g. forest communities) within a certain region is reduced. The question remains, however, whether such reduction is founded on the actual site conditions and on the actual phytocoenoses.
Before the turn of the century there was a shift from the knowledge (study) of plant communities to the knowledge (study) of habitats. It is an acknowledgement of the Braun-Blanquet method that the most widely used habitat type classification in Europe (Devillers & J. Devillers-Teschuren 1996) is in many ways based on this method itself, as well as on its findings and its review of plant communities, arranged in a hierarchical system.
If we compare Braun-Blanquet´s Phytocoenology from 1964 and van der Maarel´s Vegetation ecology, which was published in 2005, we can observe a significant development and a broad array of different approaches to the research of plants, including forest vegetation. Nevertheless, the foundations of phytocoenological study of forest ecosystems in the 21st century may stay similar to what they have been so far. This means the knowledge of plants, i.e. botanical knowledge, remains essential. A forester who is professionally active in the forest should be familiar with the flora and vegetation of his district, so botany and dendrology in the new study programmes should be taught in the same extent as before, with a sufficient number of lessons left for practical and field work. Forest phytocoenology is their upgrading and its composite part is the knowledge of different methods of vegetation analysis. There are more methods apart from the Central-European method. Lately functional approach has gained momentum in Europe in discussions and research of vegetation, especially of that in disturbed habitats, and in the study of syndynamic processes (compare e.g. Grime 1974, 2001, Klotz et al. 2002). It would be very useful for the southeastern Alpine-Dinaric region with its variegated vegetation to prepare and unify the databases of our numerous relevés, to process them and critically review the correctness of names and justification of some of the syntaxa. This can only be done with consideration of the actual site conditions and the actual phytocoenoses in nature, which means we should not act merely as statisticians or mathematicians, who hardly know anything about the forest. Forest communities, associations treated as abstract units, should be not only floristically (which can be adequately provided with a mathematical processing), but also ecologically grounded, foresters (who are the users of our research) should be able to recognise their stands in the field, and our descriptions ought to provide help to foresters in concrete interventions into the forest.
Key words: Croatia; historical development; multivariate methods; phytocoenology (phytosociology); Slovenia
|Jurjević, P., D. Vuletić, J. Gračan, G. Seletković||UDK 630* 439||63|
|Forest Fires in the Republic of Croatia (1992-2007)|
|Summary: Forest fires are generally uncontrollable occurrences that spread rapidly through forests. Depending on the age of a forest, tree and vegetation species, and the type of fire and its severity, forest fires may inflict large scale damage. These fires are predominantly induced by humans and less so by natural causes. Fires of natural origin are usually caused by lightning and in some countries by volcanic eruptions. All other fires are the result of human activity. The threat o fires differs profoundly from area to area. The most endangered regions are the Mediterranean basin, the area of North American pine forests and African savannahs. There has recently been a dramatic increase in the number of forest fires. In Europe alone there are between 30,000 and 40,000 fires annually, with burnt areas exceeding 500,000 ha. In North America, damage is far greater. Almost all fires in Europe can be attributed to the human factor. In 2007, countries along the southern edge of Europe (France, Portugal, Spain, Italy, Croatia, Montenegro, Macedonia and Albania), and Greece in particular, suffered the severest attacks owing to their climate and global changes, as well as socio-economic conditions. According to the data from the Forest Management Plan of the area, forest in the Republic of Croatia cover a total of 2,688,687 ha (2006), of witch state forests managed by the company Hrvatske šume Ltd. Account for 2,018,987 ha (75 %), forests owned by the Republic of Croatia but used by other legal persons account for 87,930 ha (3 %), while 581,770 ha (22 %) relate to privately owned forests. From 1992 to 2006, the average number of forests firs per annum was 300 and range from 109 (1995) to 706 (2000) (Tab. 1), the average annual burnt area of state -owned forests was 8,141 ha, varying from 535 ha (1995) to 39 875 ha (2000 (Tab. 4), and average burnt area of private forests (private forests owners) was 7,305 ha annually, of other forests 7,057 ha, and of forests and other soil 6,509 ha. The average annual amount of damaged growing stock and non-wood forest functions (non-wood products) was 707,427,000 kuna, and varied from 402,290,000 kuna to 2,626,332,000 kuna. The amount of damage to non-wood forest functions was estimated using the Forest Management Regulation and the Rules of Compensation for Forest and Forestland Transfer and Limited Rights (Official Gazette 111/06 and 131/06).
Key words: Croatia; forest fires; investments; organization; protection; regeneration
JURJEVIĆ, Petar ŠL
VULETIĆ, Darko ŠL
GRAČAN, Joso ŠL