Technical efficiency evaluation of forest roads with respect to topographical factors and soil characteristics

Abstract

Forest roads are usually single-lane roads built to unique technical standards with the purposes of accessing to forests and performing forestry in addition to other activities. With this study, in Karacaoren Forest Sub-District Directorate, evaluation of technical efficiency which consists of different variables of forest roads by scoring system was aimed to allow the function of the forest roads to be optimally performed over long time periods. Eleven different variables were evaluated to determine the technical efficiency of the forest roads in the study; these variables are the following: the road platform width, ditch width (condition), road expansion in curves and hairpin turns, superstructure, culvert condition, road-shadow condition, cut-fill slope stability, platform degradation, road inclination, and growth of plants on the road platform (the presence of bushy plants). The technical efficiency for each 100 m section of the forest roads was firstly evaluated in case area using the variables. Forest roads that the efficiency status was determined according to technical standards were recorded in the ArcGIS database. Finally, effects of topography (the slope, aspect) and soil characteristics on the technical efficiency variables were analyzed and mapped using SPSS and ArcGIS software. Our results showed that the “ditch width (condition)” and “platform width” variables were mostly not suitable accord-ing to the standards and the “plant growth” and “fill side slope stabilization” variables on the road platform were in good condition. The slope of the study area had a significant (p < 0.05) influence on the platform width, while the aspect of the study area had a significant (p < 0.05) influence on the ditch condition, the platform degradation condition, and the plant growth on the road platform. In general, the soil depth had some impact (p < 0.05) on the platform width, the cut side slope stability, and the plant growth on the road platform. The soil stoniness also affected (p < 0.05) the platform width, the cut side slope stability, and the plant growth on the road platform. However, the platform width, the cut side slope stability, and the platform degradation condition were all affected (p < 0.05) by erosion in the study area. Based on these results it concluded that the forest roads should be planned in sunny areas with slopes less than 51%, on “shallow soils” with “little stony” stoniness, and with “none to very little” erosion levels.