Comparison of different erosion control techniques in the Hyrcanian forest in northern Iran

The aim of this study was to evaluate the effects of closure best management practices (BMPs) on runoff volume and soil loss on skid trails that received two densities of soil cover mats and were located on two slope gradients in an Iranian temperate mountainous forest. The treatments included combinations of three closure BMPs (water bar only, water bar + sawdust, and water bar + hardwood slash), two amounts (densities) of mats (7.5 and 15 kg·m^–2), and two levels of slope gradients (≤ 20% and > 20%). Results showed that the water bar treatment was the least effective erosion control treatment, followed by the hardwood slash and sawdust treatments. Averaged over mat densities and both slope gradients, the average runoff rates and amounts of soil loss from the skid trails with the water bar treatment were 46.7 l per plot and 6.1 g·m^–2, respectively, 16.8 l per plot, 2.8 g·m^–2, respectively, with the hardwood slash treatment and 11.7 l per plot, 1.9 g·m^–2, respectively, with the sawdust treatment. The results indicated that surface cover is a necessary element for controlling erosion losses following a skidding disturbance, particularly on steep slopes.