Soil Disturbance Associated with Timber Harvesting in Southwestern British Columbia

Abstract

Soil disturbance associated with timber harvesting was evaluated in five localities in southwestern British Columbia, along transects located away from main haul roads and associated sidecast soil material. Small skid trails and associated sidecast material were included in the evaluation. Of the several disturbance indices evaluated, the percentage of area occupied by exposed mineral soil (EMS) appears to be most useful. For 13 high-lead logged sites, EMS averaged 29% and ranged from 5 to 56%. Low EMS (9%) was associated with a high-lead site logged over snow. High EMS was associated with steep slopes (greater than 70%) and shale-rich soils. Less disturbance occurred on soils derived from granitic parent materials. On two tractor-logged sites with 25 to 60% slopes, EMS was 71 and 68%, respectively. On a helicopter-logged site, EMS was only 5%. These data are compared to estimates of soil disturbance caused by logging in other regions of western North America.