Soil recovery from track construction and harvesting changes in surface infiltration, erosion and delivery rates with time

The effects of timber harvesting activities are often characterised by sign ificant changes in surface soil properties, runoff production and erosion r ates. Here we quantify trends in surface soil recovery following timber har vesting activities, specifically snig track (skid trail) construction and l agging, based on changes in soil surface compaction, infiltration, and eros ion with time since initial disturbance. Sites range in age from 0.5 to 5 y ears. Surface erosion on the snig tracks and general harvesting areas (GHA) , and sediment storage and delivery between the two areas, are measured usi ng a large rainfall simulator. Surface soil compaction shows no significant recovery over this time period, illustrating the persistent effects of mac hinery compaction on surface soil structure. In contrast, surface infiltrat ion rates on the snig tracks increase by a factor of two and snig track ero sion rates decline by almost one-order of magnitude over the 5-year period. These findings have important implications for assessing the cumulative im pact of timber harvesting activities. (C) 2001 Elsevier Science B.V. All ri ghts reserved.