evaluation of factors affecting water erosion along skid trails

water erosion causes severe soil damage in northern forests of iran which is associated with different rut depths in skid trails. the aim of this study was to assess rutting and soil displacement on skid trails to mitigate water erosion. therefore the research was carried out in eight parcels of district no 3 of shafarood forest in the north of iran. in order to evaluate the amount of erosion in skid trails, 30 lateral profiles in three slope classes (0-15, 15-25 and >25%) were randomly chosen from 10 skid trails. the amount of soil displaced and ruts were measured using lateral profile of skid trail. then the effective factors on soil disturbances such as longitudinal slope, soil texture, crown canopy and forest floor cover were separately measured in the studied plots. the results of regression analysis showed that there were significant differences between amount of soil erosion and longitudinal slope, soil texture, crown canopy and forest floor cover. the results from pearson test showed that there was significant correlation between amount of soil erosion and longitudinal slope of skid trails, soil texture and forest floor cover (?= 0.01 and ?= 0.05), but there was no significant correlation between amount of soil erosion and crown canopy. the results of this research showed that by increasing longitudinal slope of skid trail, displaced soil volume and rutting depth increased. the sample plots in longitudinal slope class of >25% and average displaced soil volume of 5.3 m3 had maximum disturbance. mean comparison test also showed that there were no significant differences in the displaced soil volume in the two longitudinal slope classes (0-15 and 15-25%), but with an increase in longitudinal slope (more than 25%), the average displaced soil volume increased.