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ŠUMARSKI LIST 9-10/2022 str. 53     <-- 53 -->        PDF

2.3. Multicriteria evaluation (MCE) – Multikriterijska evaluacija (MCE)
It is necessary to upgrade the actual with new routes of primary forest traffic infrastructure in order to achieve the targeted accessibility and reduce actually skidding distance. At this point, the question is in which area roads should be built. That issue could be solved by defining the suitability area for primary forest traffic infrastructure. The area suitable for construction of primary forest traffic infrastructure will be obtained by spatial analysis in ArcGIS 10 by using the tool Weighted Sum.
This analysis is based on multicriteria evaluation (MCE) of terrain and stand characteristics of forest area (Figure 3). The most common subcriteria used for defining suitability of area for primary forest traffic infrastructure construction in other researches are: terrain slope, growing stock and soil depth (Figure 3) (Abdi et al. 2009, Sokolović et al. 2009, Mohammadi et al. 2010, Caliskan 2013, Lepoglavec 2014, Petković and Potočnik 2018, Petković 2019, Petković et al. 2019). The suitability of area for construction was obtained by addition of standardized raster of influential factors (by Equation 3), which are weighed for each factor. Thematic maps of influential factors with resolution of 5x5 m were obtained by spatial analysis of DTM or data collected from field research and forest management documentation in ArcGIS 10. The weight of each factor means its influence on the suitability of area for forest road construction. These weights were obtained by AHP method. In order to determine weights of influential factors in defining of suitability area for forest road construction in this research a Questionnaire was prepared for assessing the impact of criteria. It was sent to relevant forest-engineering scholars for assessing. The influence of the slope, soil and timber growing stock on determination of area suitability for forest road construction is determined on the basis of opinion of 14 respondent. The average scores which were obtained by questionnaire for each criterion were standardized by Equation 3 and compared to pairwise matrix according to AHP methodology. This method was developed by Tomas Saaty (1980, 2008) and it was created as an auxiliary tool of multicriteria decision-making.
xi                    – standardized value,
Ri                    – basic value,
Rmin              – lower value of basic scale,
Rmax             – upper value of basic scale,
Xmax             – upper average value of standardized scale.
Based on the level of suitability and spatial distribution of insufficient accessible forest areas into MU, the new routes of primary forest traffic infrastructure are planned.
2.4. Designing of new routes of primary forest traffic infrastructure – Projektiranje novih trasa primarnih šumskih prometnica
The new routes of primary forest traffic infrastructure have to fulfil minimal technical requirements regulated by the Manual for designing of truck roads (Anon 2002). At the general level, they are designed by setting up the zero line on contour map by method of equal length of segments of zero line between contour lines, under constant longitudinal slope. In order to set up of zero line, it is necessary to form contours based on DTM resolution 5x5 m with equidistance of 5 m using ArcGIS 10 tool Extraction Contour. Then, contour lines should be connected with segments of zero line with equal lengths with constant longitudinal grade. The most important constructive element of zero line is maximal longitudinal grade of forest road surface, and it is 8 % (Anon 2002, Petković and Potočnik 2018, Petković et al. 2019). According to previous, minimal length of a segment of zero line is 62.5 based on contour equidistance and road maximal longitudinal grade. Setting up the zero lines is done in insufficient accessible and areas suitable for construction of forest roads in high forests. It is necessary to check a quality of upgraded forest roads network from the point of indicators of primary forest accessibility based on average targeted density of primary forest traffic infrastructure.
Two MUs have been chosen from PFC ŠUME RS, which are in two different FMAs, with different terrain and stand characteristics, which are managed by group-selection forest management system. The results of spatial analysis of DTM show that MU Prosara belongs to lowland-hilly area (91 – 362 m a.s.l.) (Figure 4) and MU Bobija-Ribnik belongs