1. Univ Talca, Dept Forest Prod, Talca 3460000, Chile 2. Paul Smiths Coll, New Mexico Forest & Watershed Restorat Inst, Div Forestry Nat Resources & Recreat, Paul Smiths, NY 12970 USAA study of soil compaction associated with four harvesting systems-a forwarder working with a mechanized harvester and a rubber-tired cable skidder, a farm tractor, and a bulldozer, each of them coupled with a chainsaw felling-was conducted in a group selection harvest of a mixed hardwood stand in Maine. The bulldozer system was associated with the highest percentage differences in soil bulk density measured in machine tracks (16.9%), trail centerlines (15.7%), and harvested group selection units (13.1%) versus adjacent untrafficked areas, whereas the forwarder system was associated with the lowest percentage differences in soil bulk density measured in machine tracks (3.5%), trail centerlines (1.2%), and harvested group selection units (6.3%) versus adjacent untrafficked areas. Results will help to inform loggers and foresters on equipment selection, harvest planning, and the conservation of forest soils and soil productivity.