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Timber Harvesting

Skyline Logging Unit

    Use the economically feasible yarding system that will minimize road densities.

  • Consider the potential for erosion and possible alternative yarding systems before planning tractor skidding on steep or unstable slopes.

  • A skyline harvest system is a good choice. This system eliminates the need for kid trails because the logs are moved to the lending by an aerial cable (skyline). By suspending logs In the air, skyline systems reduce soil disturbance. This harvest system is more expensive than ground skidding, but Is used where long, steep slopes are common. When harvesting is completed, skyline harvest areas are easily recognized by the skyline corridors. Once the timber is removed the area can be regenerated and a New Forest is free to grow.

    Terrain differences like this call for harvest techniques that consider the potential for erosion and its impact on water quality.

    A skyline harvesting system is planned for the steep canyon above. A perennial stream runs down the canyon and drains into a wetland at the toe of the slope. The skyline will operate from the road, using a suspended cable to reach down the hillside and pull suspended logs up to the road (doffed lines indicates the planned cable settings). Log landings are planned along the road. These small landings reduce the need for extensive excavation to carve out flat areas to pile logs. Notice that the harvest plan shows the boundary of the SPZ along the perennial stream, and includes the wetland at the toe of the hillside. The skyline makes it possible to harvest timber in the SPZ without disturbing the soil. Individual trees can be removed from the SPZ without the risk of damage to water quality.

    When the terrain is more gentle, other harvesting options are available. The harvest plan for this mountain bench calls for ground-based skidding equipment, pictured right photo. The slope is less than 30 percent and well suited to skidding equipment. A temporary access road (dashed line) is planned to come off the main haul road. It skirts around the outer edge of the bench and allows downhill skidding to the marked log landings along the road.
    Designated skid trails are planned for this unit (dotted lines on the map). Preplanned skid trails limit soil disturbance and any potential soil compaction. They should also be designated to avoid natural drainage areas. Skidding equipment is limited to these designated trails rather than "go-anywhere" trails. Try to confine the area covered by skid trails and landings to less than 15 percent of the total unit. Regardless of the harvest system you choose, being able to grow the next forest depends on protecting the soil.

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Idaho Forest Products Commission
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