Effect of the standard clearing limit of forest road right-of-way on stand stock growth: Case study of Vaston forests, Hyrcanian zone

Abstract

Forest roads must be constructed according to the technical standards and guidelines published by the  scientific organizations. The main aims of this research was to compare the standard clearing limit with  existence status and assess the effects of the application of improper clearing limit on forest stock growth. In this research the standard design of clearing limit was determined based on soil texture and hillside  gradient. Slope steepness map were obtained from DEM. 17 clearing limit samples were taken for each of the slope classes. The soil samples number were determined according to the length of roads which have passed from each slope classes. Results showed that the difference between the standard and existing  clearing limit in secondary forest road was significantly higher than that in main forest road. Difference  between stand volume decrease in standard and existing clearing limit in silt soil was significantly more  than that in silt clay and clay soils. The difference between standard and existing clearing limit as well as the difference between standard and existing trees stock growth in different slope classes and soil sub-units was significant. Difference between stand volume increased significantly as difference between standard  and existing clearing limit.

Key words: Forest road, clearing limit, right-of-way, stock growth, standard design.