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ŠUMARSKI LIST 9-10/2022 str. 52     <-- 52 -->        PDF

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OR                – relative forest accessibility (%),
PO          – the accessible forest area (ha),
PU                  – the total forest area (ha).
The forest is insufficiently accessible if relative primary forest accessibility is up to 55 %, it is poorly accessible if it is between 56 and 65 %, hardly well accessible if it is between 66 and 75 %, very well accessible if relative accessibility is between 76 and 85 % and excellent accessible if it is over 85 % (Pentek et al. 2005).
Efficiency coefficient of forest roads network represents the relation between ineffective surfaces, that are multiple accessible, and the total single accessible areas for double average targeted geometrical skidding distance (Pentek et al. 2005, Potočnik et al. 2013, Sokolović and Bajrić 2013a). The multiple accessible areas is obtained by using ArcGIS Geoprocessing tool Intersect as the extricate areas from single accessible areas of buffer zone around primary forest traffic infrastructure. It is calculated by Equation 2:
kU                  – efficiency coefficient of the forest road network (%),
PN                  – surface of the inefficiency of bordered areas (multiple accessible areas) (ha),
PO                  – accessible area for the chosen double aimed geometrical skidding distance (single accessible areas) (ha).
This coefficient represents grade of the impact of the forest roads on the accessibility. This efficiency coefficient should be as higher as possible, because lower coefficient means that roads are multiple overlapping and crossing.
2.2. Optimization of primary forest accessibility – Optimiziranje primarne otvorenosti
Optimization means determination of the optimal or targeted density of primary forest traffic infrastructure. The targeted density of primary forest traffic infrastructure will be determined on the basis of recommended density of primary forest traffic infrastructure for normal and intensive forest management and for certain relief regions. Targeted density of primary forest traffic infrastructure is 30 m/ha from the point of intensity forest management (Dobre 1995).
By local regulation provided targeted density of primary forest traffic infrastructure, based on the relief regions and local regulative should be:
Ø             Lowland area – 12 km/1000 ha,
Ø             Hilly area – 18 km/1000 ha,
Ø             Mountainous area – 22.5 km/1000 ha and
Ø             Karst area – 12 km/1000 ha (Anon 2015).
In general, the targeted density of primary forest traffic infrastructure is only a guide for planning of primary forest accessibility for MUs and FMA (Forest Management Administration) and it will be achieved depending on many factors. Multi-criteria evaluation of terrain and stand conditions of forest area is a convenient way for determining of relative strength of influence for each factor.