background and purpose: Logging is an example of the strongest human influence on forest environment because it causes damages to the forest soil and residual trees. The damages that occur during logging are more frequent in the skidding phase compared to the felling and processing phase. Material and Methods: The research was conducted in mixed stands of fir and spruce in the area of eastern Bosnia and Herzegovina. Felling was conducted by chainsaw and extraction by animals, i.e. by two oxen. The following data were collected: tree species, diameter at breast height, pre-bunching zone (0-30 m or 30-60 m), presence of damages, presence of old damages, number of damages, type of damage, damage position and the size of damage. Results: Damages were recorded on 3.32% of residual trees. The average number of damages per damaged tree was 1.08. The same percentage share of damages was recorded on butt end and root collar (38.46%), while damages on root have a share of 23.08%. Stem damages were not recorded. The most common type of damage was debarked tree (61.54%), then squashed bark (23.08%) and debarked and damaged tree (15.38%). It was recorded that the size of damages varied between 60 and 570 cm2. The average size of damage was 222.54 cm2. Statistical analysis using χ2 test showed significant difference in the proportion of damaged trees among different pre-bunching methods, and did not show significant difference in the proportion of damaged trees between different pre-bunching zones. conclusions: It can be assumed that oxen logging causes insignificant damages to residual trees. The results of research will be used as a basis for future studies of residual trees’ damaging during wood skidding.

UDK: 630*36:631.372]:65.015(497.6) This paper presents the research results of the skidding productivity for the Ecotrac 120V skidder in mountainous areas of MU „Igmanˮ in Bosnia and Herzegovina. Time and work study were performed. Multiple regression analysis was used for determination of work operations time consumption depending on influencing factors. The following influencing factors were recorded: the condition of the tractor road (surface), the skidding distance, the winching distance, number of pieces in the load, the volume of the load and the slope of the tractor road. The share of productive time in the total work time is 58.47%. The average value of the influencing factors was established: unloaded travel distance 585.26 m, loaded travel distance 490.49 m, winching distance 16.83 m, number of pieces in the load 5.95, the volume of the load 5.17 m3 and the volume of the piece in the load 1.02 m3. The half-tree length method was used. Standard time for skidding and daily skidding productivity were expressed depending on the skidding distance, while average values were used for other influencing factors. The standard time for skidding was 6.57 min/m3 at a skidding distance of 100 m, i.e. 17.60 min/m3 at a skidding distance of 1,500 m. The daily skidding productivity ranges from 73.07 m3/day at a skidding distance of 100 m to 27.28 m3/day at a skidding distance of 1,500 m. Comparison of the daily skidding productivity with the results of other researches showed that the Ecotrac 120V skidder in this particular case realizes approximately the same skidding productivity under similar working conditions.

UDK: 630*32:658.53(497.6 Olovo) This paper presents an analysis of full-length method used in the phase of sessile oak felling and sorting works. The aim of the research was to establish time consumption during sessile oak felling and sorting works using full-length processing method. The research was conducted in the area managed by Forest enterprise "Šumsko – privredno društvo Zeničko-dobojskog kantona" Zavidovići, Management unit "Šumarija" Olovo, Forest unit "Krivaja", compartment 112. The sampling method was applied for measuring time consumption of work operations. It was established that the share of effective time in total time was 67.12%, the share of unavoidable delay times was 30.79%, and the share of avoidable delay times was 2.09%. Time consumption of tree felling and processing was strongly affected from tree diameter at the breast height (R2=0.656). The achieved results will be used for further research on this topic, which has been unduly neglected in the past few years in the BH forestry. Further research would certainly include ergonomics, economy of work procedures, occupational safety and environmental consequences of forestry work.

UDK: 630*38:625.711.84(497.6 Trnovo) The forest truck roads, as one of the essential conditions for implementation of the planned biotechnical measures in the management unit, have to have an adequate quantity and quality. The aim of this research is determination of quantity and quality of the forest truck roads in the Management Unit (MU) „Gornja Rakitnica“, Forest Management Region (FMR) „Trnovsko“. The accessibility through wider categories of forest and total accessibility for MU have been calculated by the analysis of quantities indicators of the primary network of roads. The accessibility of the most important category of forests, from economy aspect, has been calculated – the forests with natural renewal. This accessibility amounts 12,7 m/ha. By the comparison of the values with the recommended minimum and optimum accessibility, it has been calculated that it is necessary to construct new forest truck roads. The data about quality have been obtained on the basis of terrain measurements in two forest truck roads „Rakitnica-Zućina vrela“ and „Pijevac – Borovac“. By the analysis of qualitative indicators in the analyzed roads it has been concluded that the network of forest truck roads in the MU „Gornja Rakitnica“ is passable i.e. it enables implementation of planned activities from all forest fields. The technical elements of the measured roads enable the values defined by technical regulations. The constructive elements: carriageway condition, slope cuttings, ditches and objects on the road are not in an adequate condition. If the adequate recovery works are not undertaken it could cause progressive deterioration of roads, which could influence functionality of roads transport of timber, access to compartments, etc… For the improvement of the condition of forest truck roads, the measures of recovery have been designed and the calculation of total and average costs has been carried out.

The notion of energy chain concept has been defined as the trajectory of energy transformations from the fuel source or energy sources to useful energy form to end users. Production of fuels, heat and electricity from different sources is defined by the appropriate energy supply chain. Every single energy supply chain can be uniquely defined by several sustainability criteria. These criteria are: total energy efficiency of production, total exergy efficiency of overall chain, the coefficient of exergy quality for different products at energy chains, economy of production, investment and environ‐ mental criteria. Optimal energy supply chain can be chosen by using multicriteria optimization which fulfils the above-mentioned sustainability criteria. This selected energy chain is close to ideal solution. The ideal energy supply chain is formed from the set of energy production ways which are defined from the perspective of sustaina‐ bility criteria and which have connection with the current status of technologies, economic, environmental parameters, etc. The concept of optimization in practice is usually based on economics until recently, often neglecting all the other consequences of such a decision. Therefore, multicriteria decision making (MCDM) improves the opportunities in assessing the optimal variant of energy chain for defined ranking criteria. Before the optimization process, it is necessary to create a mathematical model for calculation of optimization criteria. Also, for each specific case of energy produc‐ tion, it is necessary to develop appropriate mathematical formulas to describe the energy chain. Numerical verification, all mathematical calculations and modelling have been applied and confirmed on wood biomass supply chain for energy production in this case. The reason for this is complexity of supply chains in the bioenergy and representation of renewable energy sources. For total ranking of energy chain for production of fuel or energy and selection of optimum variant, the multicriteria optimization and VIKOR method were applied. The significance of energy produc‐ tion from renewable energy sources is particularly expressed nowadays. Basically, the most significant part in the process of energy production from energy sources is the © 2016 The Author(s). Licensee InTech. This chapter is distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. supply chain, final conversion of energy in useful form at the energy plant and the distribution process to end users. Due to the fact that there are various opportunities for the composition of energy chains of fuel supply and different ways of energy production, it is necessary to try to make a unique mathematical approach for this problem. With the proposed sustainability criteria and developed mathematical model, it is possible to unify the overall problem of energy supply chains’ optimization. The proposed developed method can be used for the optimization of any kind of energy supply chains (electricity, heat, fuels or their mix). All of these are enabled by proper selection criteria for the description of overall energy transformations in energy chains and quality evaluation of the energy produced. The developed approach and mathe‐ matical model have a very practical application in the selection of optimal variant of energy production and of course in designing new energy chains.

Production of solid fuels from wooden biomass is defined with appropriate energy chain of sup ply. Production procedure of solid fuels from wooden biomass, starting with technology for gathering wood residues and residues from logging up by the system of fuel production (system for milling, crushing, chopping, drying and pressing of wood residues), represents the energy chain of supply of solid fuel from biomass. Every single energy chain of supply and production of certain form of solid fuel from wooden biomass can be uniquely defined with three general criteria. These criteria are: energy efficiency of production, economy of production and environ mental criteria. Efficiency of production is the relation of overall energy consumption per 1 kWh of heating value of produced fuel. When we talk about the economical aspect of production of solid fuels we take into account all production costs per 1 kWh of heating value of biofuel produced. Forest biomass is scattered and the need for its collection and transport require certain consumption of fossil fuel. Consumption of fossil fuel is needed to run mechanization to collect, transport and prepare biomass. Consumption of fossil fuels causes the emission of GHG. Ecological criteria for the estimation of production process of bio energy can be defined as emission of GHG per 1 kWh of heating value of produced fuel. Besides general criteria to estimate the quality of production of energy from biomass, there are specific criteria. Specific criteria regard ing several characteristics are tightly related to applied technologies, potentials and barriers during the use of biomass. This paper analyzes only specific investment in selected chain of en ergy supply. The paper mathematically describes four characteristic cases of solid biofuel production from wooden biomass. These cases are: production of wooden chips from forest biomass with mobile chipper, production of wooden chips from wooden residues transported from sawmill to processing terminal, production of wooden briquette from mill residues transported into briquette factory, production of wooden pellet from mill residues transported into pellet factory. For overall ranking of energy chain of wooden biomass supply and selection of optimum variant, multicriteria optimization and VIKOR method is used.

The development of technology and the means of labour in the technological process of forest harvesting in FBiH mainly depends on the factors related to the specific manner of forest management. The dominant share of mixed tall forests with natural regeneration, the selective manner of management and rather difficult natural conditions have resulted in the application of the cut-to-length method and to a lesser extent, the tree-length and semi-tree-length methods. On the basis of expert classification of the development phases in forest harvesting, it can be noted that wood assortment production in FBiH is currently partially mechanised. With the aim of defining measures for increasing productivity, lowering the costs and a greater humanisation of work, there has been an analysis of the current state of the means of work in all three phases of forest harvesting. The analysis included the following parameters: number of means in different phases, the type, the average age, ownership and technical planned obsolescence. All the data were collected through a survey which included all stakeholders (cantonal forest companies and private contractors). The results showed a satisfactory state only when chainsaws are concerned, i.e. the rather cheap tools. Other equipment (adapted tractors, skidders, trucks, etc.) has largely reached planned obsolescence. Their old age results in a low level of utilisation, i.e. an insufficient amount of working hours per year which eventually leads to a decrease in productivity and increase in expenses. Based on the data, it can be concluded that it is necessary to begin the process of new mechanisation procurement and the replacement of existing, time-worn and technologically obsolete machines with new ones. At the same time, it is clear that, in the conditions of low availability of investment capital and cheap labour force, this has to be a gradual process. In relation with this, the process should start in the most expensive phase - timber extraction, i.e. the phase in which the economic efficiency is unquestionable.

UDK: 630*38:625.711.84(497.6 Sarajevo) The time period of forests opening and construction of forest truck roads in the analyzed area is longer than half of century. In such long time interval different types of vehicles for transport of timber assortments have been applied. Due to this fact technical elements of constructed roads are different. The vehicles currently used for the transport of timber assortments cause an accelerated destruction of forest truck roads due to inappropriate carriage way quality. Besides traffic load the forest truck roads are exposed to permanent atmospheric influences. The above specified and other reasons condition obligatory and regular maintenance and reconstruction of forest truck roads depends on the current condition of forest truck roads as well as on the plans for further use. In this article the condition of forest truck roads in the Forest management regions of Sarajevo Canton has been determined. The most frequent types of damages and causes of their occurrence have been registered. The methods for maintenance and rehabilitation-reconstruction of forest truck roads have been selected and their costs have been calculated. In the time when construction of new kilometers of forest truck roads is more and more rare, timely, adequate and financially justified maintenance of the existing network of forest truck roads is one of the key question for their undisturbed use. On the basis of results obtained in this research the guidelines for the time period and the ways of maintenance of forest truck roads have been given. The application of these guidelines should help in achieving of the best and most economical total results through the long-term use of forest truck roads.

UDK 630*38:551.311.21          625.711.84:551.311.21 Tractor roads are often, due to un-implementation of appropriate rehabilitation measures, exposed to erosion processes of various intensity. These processes can be particularly expressed upon completion of forest harvesting works if natural conditions also have such character which favors intensification of erosion process. Intensification of erosion processes on tractor roads in post-exploitation period most often occur in cases when surface water appears on ruts. More intensive coverage occurs in cases when tree crowns do not cover tractor roads, i.e. if larger opening (of forest crop) is in close vicinity of tractor road, which enables larger presence of light and more intensive vegetation growth. This document applies erosion process intensity degree method and assessment of degree of coverage or coverage by litter. For assessment we used a scale from 1 to 5 (REBULA, 1991). Erosion intensity degree on observed locations goes from 1,86 to 3,73. Coverage of tractor roads by grass vegetation or coverage by litter is in range from 4,91 to 1,86.

UDK 582.475:581.4(497.6 Olovo) The research has been carried out in a formal experiment with silver fir near Očevje-Olovo, with nine provenances originating from natural BiH population of 22 years of age. The research observed following provenances: communities from the area of Bugojno, Bosanski Petrovac, Olovo-Palež, Olovo-Klis, Pale, Konjic, Fojnica, Sokolac, and Prozor. The analysis of diameter on the root collar found that there are statistically significant differences among the provenances. It was also found that the biggest diameter on the root collar was on the provenances of Fojnica, with 75.6 mm, whereas the smallest was on the provenances of Olovo-Klis, with 65.2 mm. In terms of breast height diameter, some statistically significant differences were also found, so that the biggest diameter was on the provenance of Fojnica, with 47.0 mm, whereas the smallest value of this feature was on the provenance of Pale, with 41.6 mm. The analysis of the height of different provenances for the testing period, 1999 – 2005 (7 years), suggested statistically significant differences among the provenances. The biggest value was on the provenance of Bosanski Petrovac, with 407 cm, whereas the smallest height was on the provenance of Olovo-Klis, with 364 cm. The results obtained during this research provide valuable information, which can be used as indicators for successful differentiation of silver fir.

UDK 630*31/*32:621.936.6(497.6 Vareš)           621.936.6:621.892(497.6 Vareš) Chainsaw is the main tool for work, considering the terrain and soil in our country, in the process of the harvesting, and there is a big chance it will be the main tool in the future too. The goal of the research is to determine fuel and lubricant consumption of the chainsaw Husqvarna 372 XP, during the harvesting and making forest wood assortments, on the area of the Public enterprise forest, Vareš, section 37. During the research, 50 trees of the fir and spruce have been felled. Range of the diameter was from 8 to 76 cm, and the volume of the assortments was 86.16 m3. Volumetric method is applied in the measurement of fuel and lubricants, with precise determination of how much fuel it was in the thanks. Analysis showed that there is a strong correlation between consumption of the fuel and lubricant (L/m3) in relation to the size of the breast height diameter. Average fuel consumption in the process of logging and preparation was 0.104 L/m3, while the average consumption of lubricant was 0.023 L/m3. It is necessary to continue to pay great attention to the rationalization of consumption on fuel and lubricants, as well as reducing their harmful effects on humans and environment (introduction and usage of biodegradable fuels and lubricants).