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Zadovoljstvo nam je obavijestiti vas da je 2011. godina na poticaj Republike Hrvatske Rezolucijom Opće skupštine UN-a 61/193 iz 2006. godine proglašena Međunarodnom godinom šuma i da se održava pod temom »Šume za ljude i iskorjenjivanje siromaštva«. Republika Hrvatska od samih je početaka aktivno uključena u rad Foruma za šume Ujedinjenih naroda. Forum za šume Ujedinjenih naroda (UNFF) međunarodna je organizacija koju čine sve države članice UN-a i specijalizirane agencije, a predstavlja krovnu međunarodnu organizaciju u šumarskoj struci koja određuje smjer razvoja šumarstva na globalnoj razini. Osnovna je zadaća Foruma za šume Ujedinjenih naroda uspostava globalnoga održivoga gospodarenja šumama…

Vehicle movement in forestry is described by: 1) the basic dimensional features of the vehicle, 2) the ability to overcome obstacles during movement, 3) traction performance, and 4) environmental suitability. Traction performance depends on the ground conditions (soil bearing capacity) and the total effect of all forces on the vehicle. In this article, skidder traction performance is described with gross (κ) and net (µ) traction factors, wheel slip () and wheel efficiency () in downhill timber skidding in order to create a gradeability model for skidders in terms of wood harvesting. In downhill skidding (slope of 15 % and 30 %), the skidder is under great influence of parallel force component (G sin α), adhesion weight (Ga) and slope, which combined resulted in a negative traction force (Fv). Along with the negative traction force, torque (M) and thrust force (Fo) were also negative. The vertical component of the rope force (V) was always greater than the horizontal component of the ropeforce (H). If the horizontal component of the rope force is equal to zero (H = 0), i.e. the moment when the weight of the load (Q sin α) and resistance to traction are in equilibrium, the slope angle a, shown in Figure 1, is a function of load mass distribution factor (k) and skidding factor (µp). This is a »turning point« because the loads start to push the vehicle down the slope, which results in a negative horizontal component of the rope force (H = –0.247 kN). The load mass distribution factor ranged from 0.31 to 0.58. The factors of gross and net traction were also negative because positive traction force could not be achieved. The net traction factor (µ) ranged from –0.15 to –0.29, and gross traction factor ranged from –0.17 to –0.41. The wheel slip was also negative, but lower in value when load mass was increased. The wheel efficiency ranged from 0.30 to 0.71. In downhill skidding (on slopes of 15 and 30%) there is no positive traction force because of the constantly present engine braking (Fo=0), and this is the second »breaking point« (critical slope). The slope angle α (as shown in Figure 1) is now a function of many factors.
In downhill skidding, the most important is to avoid blocking of the wheels, which would lead to a complete vehicle slippage. The driver must be constantly aware of that fact. When the load pushes the vehicle down the slope, due to the constant thrust of timber at the back end of the skidder, it can be concluded that, in a due time, such performance will result in fatigue of the material and premature damage to the vehicle. It is necessary to additionally explore the effect of downhill timber skidding on the psychophysical state of the driver, and establish how technical soundness of the vehicle is reduced, over time, due to engine braking and pushing of the vehicle by the load. Due to a generally acceptedfact that skidders should operate in uphill motion up to 30% and in downhill motion up to 45% of terrain slope, further studies should be done.

Keywords: skidder, traction performance, slip curve, braking force, downhill skidding

This paper reports on the research of organizational culture in Croatian Forests Ltd. The employees of Croatian Forests Ltd. were questioned about comprehensive management and business issues in the company. The research was focused on examining the current state of organizational culture in the state forestry company. The questionnaire on the attitudes of employees covered 49 forestry office managers within the company. The survey covered their views on organizational features, management practice, process of decision making and setting priorities in the company, obstacles and advantages in management, as well as other indicators of organizational culture. The results of research point to an adverse situation and the need to change and improve the organizational culture. Approximately two thirds of employees consider standardized rules, a strict hierarchy and bureaucratic way of functioning as a major company feature. The aim is to provide information about the organizational culture in Croatian forestry, raise the forestry profession awareness about the importance and role of the organizational culture, and to highlight the need to encourage and develop a culture as an important advantage. The findings and reports of the research can represent an objective starting point in designing strategies for improving management practices of the company.

Keywords: forestry, organizational culture, management and leadership, business improvement

Bark is the outer layer of the tree made of its inside and outside part. Out of all bark features, the most important is its thickness and share in volume of trees and processed logs. In the process of timber harvesting, during scaling of processed logs, in Croatian forestry, two-entry tables are used (wood species and diameter over the bark) for deduction of double bark thickness that are not the result of scientific research.

The aim of this paper is to investigate bark features of black alder with respect to: (1) bark share in tree volume, (2) bark share depending on relative tree height and (3) dependence of double bark thickness on diameter over the bark. The research was carried out in the Management Unit »Đurđevačka Bilogora«, in the private stand generated by afforestation. The sample involved 35 model trees of black alder, 5 in each thickness class, from 7.5 cm to 37.5 cm. The determination of the volume of model trees was carried out by the sectioning method. The research of bark features of black alder has shown as follows:

• By the increase of DBH, bark share in the volume of large-wood decreases exponentially from 23.6% (7.5 cm DBH) to 16.4% (37.5 cm DBH),
• By the increase of the relative tree height (h/H), the bark share increases linearly from 17.8% (butt) to 21.8% (top of the tree),
• By the increase of diameter over the bark, double bark thickness increases exponentially from 0.9. cm (7 cm) to 2.7 cm (37 cm).

The results of research have indicated the need to:

• Make further research of the dependence of double bark thickness on the diameter over the bark of commercial wood species – and thus provide impartiality between buyers and sellers,
• Use the possibility (by incorporating it into applicable laws) of deducting the bark on logs with respect to the share of bark in the volume depending on diameter over the bark (which is in accordance with the Croatian norm HRN EN 1309–2:2006) – and thus provide the rationalization of production and final products, respectively.

Keywords: bark thickness, Black Alder, timber scaling

Research results of mechanized felling and processing by harvester Timberjack 870 in the black pine forest culture are presented in this paper. Special emphasis in the research was on the impact of tree’s forkness on work productivity. Time consumptions were recorded by snap-back chronometry method and paired with DBH of felled and processed trees. Equation for dependance of tree’s net volume (v_net) on DBH was established in the separate sample of trees in the same felling area: v_net = 0.0003 DBH^2.16 [m³]. Using the mentioned equation transformation of production unit from tree with known DBH to net volume was done. Time consumptions of individual work elements were grouped in three clearly separated work components: vehicle moving, trees felling and wood processing. Regression analysis of time consumptions dependance on treešnet volume was conducted. For work components vehicle moving and trees felling dependance wasn’t found, while for work group processing medium dependance was established. Qualitative variables tree’s straightness/forkness (PR = 0 for straight trees, PR = 1 for forked trees) were added to data pairs of tree’s net volume and time consumption for processing (t_i) and multiple regression was done. Strong corelation (R = 0.5964) was established.
Productivity model: V_h = (60 v_net) /f_d (t_v + t_s + t_i) [m³/h] was constructed; with allowance time factor f_d = 1.26 (Krpan & Poršinsky 2002) and driving (t_v = 0.24 min/tree) and felling (t_s = 0.15/tree) time consumptions as medians.
With this model 70% decrease in productivity was calculated for forked trees of 10 cm DBH and 50% decrease for forked trees of 40 cm DBH in comparison to straight trees of the same DBH.

Keywords: mechanized felling, harvester Timberjack 870, productivity, tree’s forkness

Explanation of safety trends in the state and private Croatian forestry sector is given in the introduction. Emphasize is placed on extremely vague and unclear picture of safety and work control of forestry workers employed in the private sector. In the central part of the paper, according to foreign experience, in the framework of safety responsibility model development, definition is given of roles (forest owner, forest operation manager, contractor and subcontractor) and assignments that need to be accepted and executed by the participants in the chain of timber harvesting in private forest land. At the same time, emphasize is put on the significance of cooperation and transfer of necessary information to all participants in the production chain. The final section gives guidelines to promote safety, health and work control in the private forestry sector through education and training of all stakeholders regarding health and safety roles and tasks that need to be accepted and implemented in the operational performance of forest work. The current state of safety can be improved through the establishment of a national safety responsibility model in private forestry sector, where the first step would be to develop a legal framework.

Keywords: forest sector, health and safety, safety responsibility model, entrepreneurs in forestry

Designing forest roads is a very important phase in the management offorests and forest resources. The design of a forest road consists of two sub-phases. The first, field sub-phase, involves the collection of field data necessary for making the project of forest roads. The second is an office sub-phase, which consists of entering data, obtained by field survey, in a computer program with the aim of making the main project of forest roads and printing all the elements of the main forest road project.
Using new computer software greatly reduces the time needed for completing the main design. Today there are many computer programs that are primarily specialized in the design of public roads, some of which stand out with their applicability in forestry in the design of forest roads. This paper describes such a software package.
The ROADPAC software package was developed by the company »Pragoprojekt« from Prague. It was aimed at developing the whole project documentation for the construction of highways, and public andforest roads. It works in Windows (all versions up to Win 7), the interface is an interactive program that allows continuous control of all sections of forest roads during input and correction of data. One of the important features of this software package is that it is tied to AUTOCAD. It provides detailed data processing and other applications that support.DXF format making it easy to print the project documentation in different scales and paper formats.
In ROADPAC package, a specific program is selected in the menu located in the bottom row of the fixed part of the panel dialog. The programs of the first five groups are programs for calculating the data, while the sixth group includes graphics programs, for the preparation of drawings;
Group 1: Calculation of Horizontal Alignment
Group 2: Terrain Data and Geology
Group 3: Vertical Alignment
Group 4: Cross Arrangement
Group 5: Cross Sections
Group 6: Drawings
Input data are obtained by completing and editing tables, or by clicking on the controls placed on forms that appear in the computer screen.
Subprograms are presented in Table 1 and further in the text some subprograms that are essential in making the project of forest roads are explained;
Program RP12 »Horizontal Alignment« is used to create situational draft of forest roads,
Program RP27 »Terrain Cross Sections« calculate cross-sections from field data,
Program RP28 »Addition of Geology« is used to add or correct geological and soil data in the file,
Program RP31 »Vertical Alignment« is used to calculate the longitudinal section,
Program RP34 »Drawing of Longitudinal Profile« is a designing file that contains symbolic drawing of the longitudinal profile,
Program RP41 »Automatic grading details according to ČSN« prepares the basis for shaping the road width in accordance with the principles of a new Czech national standard (CSN) 736 101 (published in 2004), which is based on the calculation of the axis of the road and situational draft,
Program RP51 »Cross Sections Construction« constructs cross-sections, using their own input data and results from RP43, RP31 and RP27. This program can monitor programs RP53, RP83 and RP71,
Program RP71 »Earthworks Calculation« is designed to handle the amount of earthworks in the design as the final program for the determination of the cut and fill,
RP80 Program »Pavement Reconstruction« uses the archive files on horizontal and vertical road alignments and cross sections of ROADPAC file type, or the results of RP12, RP31, RP43 and RP51,
Program RP83 »Drawing of Perspective Views« is used as the final process of designing the road program, with various perspective views in 2D or 3D,
»VIANIV« is a program for interactive design and editing situations. The program is a part of ROADPAC software package, but can operate as a standalone program outside of the package.
The section that follows deals with the entry and processing of data, required for the design of forest roads; Fig. 2 presents the entry of coordinates of polygon points. Fig. 4 shows the input of station, Fig. 5 shows the data input of the transverse terrain profile, while Fig. 7 shows the longitudinal profile entries. Further in the text, description is given of the program for data entry on cross section, pavement extensions, entering of details of the excavation and embankment slopes and finally the program for printing the project documentation and software for different perspective views (2D and 3D).
In the concluding remarks, some of the benefits of the ROADPAC program package are described in relation to the program »Cesta« commonly used in Croatia.

Keywords: »ROADPAC« software package, Design, Public Roads, Forest Roads

Decision making in forestry is characterized by multiple goals of management and by a wide specter of stakeholders, where the choice among the decision alternatives on any level of decision making or in any time horizon must take into consideration different values that are not directly comparable, and face the uncertainty of their implementation. Multiple-criteria decision making models are one of decision support tools, from which the theoretical basis and the forestry related implementation of the Analytical Hierarchical Process and Analytical Network Process have been presented. These models have been developed in a conceptual framework of research of sustainable forest management with the incorporation of opinions of experts and stakeholders, which secures the possibility of implementation of the preferred alternative. As a contribution to the framework, a preliminary model of the analytical network process for operational management of economical forest has been made, and the possibilities of the implementation of the respective models have been analyzed.

Keywords: Multiple-criteria decision making models, AHP, ANP, sustainable forest management

This paper describes the procedure for the adoption of CEN standards and the types of normative documents. A list is given of all documents of the Technical Committee 335 – Solid biofuels, which covers the standardization of energy wood chips. The standard EN 14961–1:2010 Solid biofuels – Fuel specifications and classes – Part 1: General requirements, prescribes the specifications of energy wood chips and gives references to the standards that deal with specific characteristics. As according to the above standard, it is a must to specify the size, moisture and ash content for wood chips, a short explanation of the general principle of the required analysis is given along with the classification based on limit values, as well as the description of the impact of individual characteristics on the use and trade of energy wood chips. The research results are also presented of natural drying of stacked oak and ash energy wood.

Keywords: wood chips, CEN standard, granulometric structure, moisture content, ash content