DIGITALNA ARHIVA ŠUMARSKOG LISTA
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|ŠUMARSKI LIST 1-2/2015 str. 44 <-- 44 --> PDF|
Table 6 reveals that buffer strips method has a general tendency of slightly over estimating the SDs values reported by the grid point methods, while the CGR method has a tendency of under estimating these values. The buffer strip method is more accurate than the CGR method and hence is recommended for use in practice.
Correction factors – Faktori korekcije
The extraction coefficient (ks) is a good qualitative indicator of the skid trail network. When ks values are closer to 1 (ideal case), the skid trails are straighter and have lower gradients. This study reported ks values between 1.13 and 2.16 (Table 7). Considering that methods G100, G50 and G10 are within the established accuracy threshold, the statistically sound values of ks vary between 1.13 and 1.79 and an average value of 1.50 is recommended for use in practice. This is similar to previous literature findings (Amzica 1971; Bereziuc1981) regarding mountain forests in Romania (Table 9).
In respect to the network correction factor (kn), in the hypothesis of a two sided opening of the studied forest area (Table 8), the values reported by scenario Zero vary between 2.52 and 3.01. These values are considerably higher than those reported in literature (Table 9). This situation reflects the current uneven distribution of the roads in the studied forest area. In scenarios proposing new roads (FR1 to FR3), kn values are lower (from 1.65 to 2.15). This means an improvement of the location and spatial distribution of the roads within the new forest road network. The hypothesis of one sided opening of forests seems to better explain the current infrastructure conditions (scenario Zero), kn values ranging between 1.26 and 1.50 (Table 8). This explains the current practices in the study area where all harvested timber is extracted downhill to the existing valley roads located at the edge of the forest area. Scenarios FR1, FR2 and FR3 are closer to the ideal model for one sided timber extraction, with values of kn between 0.97 and 1.08 (methods G100, G50 and G10). This situation can be interpreted as close to optimum located forest roads in the ideal theoretical ¸