Skidding logs from stump to landing areas is one of the most important procedures in ground-based logging operations. Rubber-tired skidders often increase soil compaction, which leads to an increase in soil strength (penetrometer resistance) and bulk density (dry soil weight per volume). Woody slash materials (tree limbs and tops) are generally distributed over the skid trails to reduce soil compaction due to machine traffic. In this study, soil compaction was estimated by measuring the values of soil strength and bulk density resulting from a rubber-tired skidder. The effects of not only woody slash materials but also various other slash treatments (chip and sawdust) in reducing soil compaction were investigated by considering the various numbers of vehicle trips (1, 5, and 10 trips) and two soil depth classes (10 and 20 cm depths). The results indicated that soil compaction indicators, soil strength and bulk density, markedly increased as the number of machine trips increased. Woody slash materials distributed over the skid trail provided better soil support capacity than that of other slash treatments. It was also found that there was a significant correlation between soil strength and bulk density with respect to the number of machine trips and slash treatments.