survey of directional felling and analysis of effective factors on felling error (case study; iranian caspian forests)

economic and environmental logging is important for sustainable wood production in the caspian forests, north of iran. predetermination of the skid trail network and directional felling is a usual recommended method to reduce logging impact. the aim of this study was evaluation of directional felling and finding factors effective on felling error. totally 135 trees were selected randomly for directional felling in mountainous forest in nav watershed in the caspian forest. felling error was calculated for each observation in relation to lay deviation of ground slope, tree length, tree lean, the extent of rot on stump, and tree volume using multiple regression models. tree volume, interaction of tree volume and terrain slope, and extent of rot in the stump were the most influencing factors on felling error. results suggest that felling workers should be enough trained for proper use of tools and equipments. the most common tools and devices for manual felling are wedge and hydraulic jack which should be provided in advance.