Assessing the effectiveness of mulch strips for the mitigation of soil erosion on skid trails in a north mountainous area of Iran

Forest operations on skid trails affect forest soil and represent the most important source of sediment. The aim of this study was to assess the effect of sawdust (a waste product of woodworking operations) in reducing runoff and soil loss for clay loam soil on skid trails. Treatments based on the combinations of three levels of traffic intensities (3, 7, and 15 passes), two classes of slope gradient (≤20% and >20%), two types of mulch cover (sawdust—thickness of 1 cm, 5.7 kg m−2—and bare soil), and three levels of mulching area (1/3, 2/3, and 3/3 of plot length) were considered. For each treatment, three replications were included. Under natural rainfall, the higher the traffic intensity and slope gradient, the higher the average volume of runoff and soil loss (1.21 mm and 5.29 g m−2). A significant enhancing effect on the volume of surface runoff and sediment yield throughout the skid trail was recorded on mulch cover treatments. On the trails, segments treated with sawdust cover (SC) (0.34 mm and 0.90 g m−2), the average runoff and soil loss were lower than on untreated bare soil (BS) segments (0.60 mm and 2.05 g m−2). Mulching was more effective in terms of reducing runoff and soil loss when applied over the entire plot length than over strips of 1/3 and 2/3 of the plot’s length. Trail surface mulching is a successful measure to control soil losses during skidding disturbances, particularly on trails with steep slopes.