The following are verbatim excerpts from the report written by the Forest Service. Soils on slopes of the Coast Range are prone to sliding and slumping, especially following heavy rainfall. These landslides create large debris deposits in stream channels, often causing temporary degradation of fish spawning and rearing habitat. However, over the long-term these provide renewed sources of large wood from uprooted trees which move into and through stream channels, increasing channel complexity, moderating stream energy and creating new fish habitat.
Landslides associated with clearcuts or roads usually lack large wood, but are rich in sediments.
They often travel farther downstream, deeply scouring some stream channel sections and depositing thick sediment layers in others, which limits type and diversity of fish habitat. When this occurs repeatedly over entire stream systems, fish stocks may be severely depleted. Instead, landslide rates for slides associated with boath roads and clearcuts were calculated based on clearcut acres only. This was done to display the significant increase in slide rates associated with management activities when those associated with roads are included. Since acres of road in the Coast Range forests are fewer than acres of clearcut, the actual slide rates associated with roads only would be much higher if road acres were available for this assessment.