Ground based operation effects on soil disturbance by steel tracked skidder in a steep slope of forest

Abstract

In this study, the effects of slope and traffic intensity on soil compaction, rutting and forest floor removal was evaluated on a skid trail in the natural forest of north of Iran. Combination of two levels of slope < 20% (SC1) and > 20% (SC2) and three levels of traffic (one, five and nine traffics) were studied. Treatment plots, with three replications, were established on the skid trail prior to skidding. The results of this study showed that all bulk densities were considerably higher in SC2 than in SC1 and average soil bulk densities were measured from 1.07 (g∙cm^–3) to 1.23 (g∙cm^–3) on skid trail and 0.91 (g∙cm^–3) in undisturbed areas. With the increment of traffic, soil compaction increased but there was no significant difference among the three levels of traffic frequency in SC1 whereas it was significant between one and five cycles in SC2. Greatest rut depth was measured as 12 cm at nine traffics in SC2, although increase of traffic density caused deeper rut depth at all slope treatments, but it was higher at the SC2 in comparison to SC1. Litter mass decreased considerably on the skid trail with the increasing in slope and traffic. No important difference has been detected between SC1 and SC2 in terms of Litter mass removal. These results provide clear evidence that soil disturbance on steep trail is intensified.