Soil compaction from low ground-pressure, torsion-suspension logging vehicles on three forest soils

Monitoring soil density on three sites during repeated trips with a high-speed skidder showed that: During the first 20 trips, soil density primarily increased between depths of 2 to 4 inches; Density increased most during the first few trips; Density continued to increase slowly in amount and depth with the number of trips, especially as the litter layer was removed; The litter and slash layers tended to remain in place for the first 20 trips; As slope increased, fewer trips disturbed more surface soil; In western Oregon on two sites with slopes under 30 percent, skidding disturbed 12 to 15 percent of the surface area; In western Oregon, skidding heavily disturbed 2 to 3 percent of the surface on two sites; and In eastern Oregon, 20 trips by the machine exposed mineral soil on about 20 percent of the surface area of a skid trail.