Soil Displacement and Compaction

Erosion

Soil erosion and displacement occur through the removal of topsoil by machinery. This can lead to reduced stream water quality through sedimentation. In forests, erosion (at right) is typically caused by surface or overland water flow on sloping terrain that has been cleared of organic matter. In many regions, chemical control of weeds has reduced the need for soil tillage and thus reduced the occurrence of erosion. Orienting site preparation operations and skid trails along slope contours can minimize the risk of soil erosion and displacement. Forest roads are also an important potential source of sedimentation in streams, yet such effects can be mitigated through the use of Best Management Practices developed by the USDA Forest Service and collaborators at such experimental watersheds as Coweeta Hydrologic Laboratory and the Fernow Timber and Watershed Laboratory (see Forest Roads; Stickney and others 1994).

Soil compaction may occur as a result of the use of heavy machinery during harvesting and site preparation operations. This also has the potential to decrease soil productivity, yet few, if any, long-term research trials have documented lasting decreases in forest productivity due to soil compaction across harvested land (e.g. site not located directly on skidder roads and landings) (Morris and Miller 1994; Burger 2002; Powers and others 2005; papers following Powers 2006).