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ŠUMARSKI LIST 3-4/2017 str. 63     <-- 63 -->        PDF

technology. Considering the mentioned literature, road length, density, spacing and coverage were calculated as 226.34 km, 11,74 m/ha, 851,7 m, and 51% respectively for the entire study area. 184 km of the existing roads have a longitudinal slope greater than 10% and 42 km have a long slope greater than 12%. (Figure 7).
Timber extraction systems were determined on the basis of ground slope, extraction direction, extraction distance, forest road network, elevation and boundaries. Spatial location of five selected systems as; chainsaw-agriculture tractor, chainsaw-forest tractor, chainsaw-small size cable crane, chainsaw-medium size cable crane and chainsaw- sledge yarder are shown in figure 8 according to our model considering above mentioned parameters and influencing factors such as technical limits of felling and timber extraction.
Outputs of the developed model displayed that, chainsaw–small size cable crane (36.76%) and chainsaw–medium size cable crane (27.94%) systems covered the largest forest area followed by chainsaw–forest tractor (23.52%), chainsaw–agriculture tractor (10.29%) and chainsaw–sledge yarder (1.49%). The model presented in the paper was developed as a tool for planning forest operations.
There is no recorded study in the literature about determining timber extraction system considering five different systems. There are some studies exist, however they generally focus on one system and basically analyses the cost or efficiency of the selected method or the system. Therefore, the outputs of the conducted study couldn’t compare with similar studies. On the other hand, a few studies conducted for the allocation of timber extraction systems but under different conditions. For instance, Pentek et al., (2008) developed a model for selecting a harvesting system for commercial forests of Northern Velebitis based on three influencing factors: terrain slope, extraction distance and breast height diameter of trees. Based on the model, a harvesting system is determined for each forest sub compartment. The results show that breast height tree diameter restricts mechanized felling and processing. They found that considering the fully mechanized nine harvesting systems, only over 7.27% of the researched area could be used.
CONCLUSIONS
ZAKLJUČCI
The results of this study put forth that GIS is one of the most valuable tools in locating and analyzing mountainous areas for forest road network planning and model for timber extraction system.
The maps of elevation, slope, aspect, forest road network and timber extraction were prepared and classified. In this study the total length of existing forest road network was 226,34 km, road density was 11,74 m/ha, road spacing was 851,7 m and road coverage was 51%. The GIS based timber extraction model, presented in this paper, has been developed for planning in harvesting operations. The timber extraction systems were determined on the basis of factors, such as slope, extraction direction extraction distance, existing forest road network, elevation and boundaries. While the forest road network allows access to the forest area, the system of timber extraction can be considered as the technical limit which defines the part of forest that can be managed with the present roads. The model selected timber extraction systems as; steep terrain chainsaw–small size cable crane (36.76%) and chainsaw–medium size cable crane (27.94%) for the study area.
In conclusion, options for more economically and environmentally friendly timber raw material production planning became more evident for the planners. The results showed that we could provide an integrated harvesting operation solutions for a characteristic mountainous area in Turkey based on GIS techniques.
The methodology developed for this study can also easily be applied to the other planning units as long as the requirements are met such as digitized contours, existing roads and boundaries.