can be consistently obtained using a contrast stretching routine and threshold classification. The savings in time 
and cost to survey soil disturbance on clearcuts will be substantial for the forest industry in the long run. 
5.0 FUTURE WORK 
Additional analysis of units within the CP# 140 for the Likely area on 229 mm X 229 mm color aerial 
photographic prints with a scale of 1:5000 is in progress. Computer digitization of color 35 mm and 70 mm 
aerial transparencies showing clearcut units near Golden, British Columbia, at a scale of 1:200 will be carried 
out to study soil disturbance using this image analytical technique. 
6.0 ACKNOWLEDGMENT 
Advice and interest of R.B. Smith, Project Leader, and D. Winston, Program Director, Pacific Forestry Centre, 
are greatly appreciated. The author wishes to thank M. Wilkins, Chairman of B.C. Interior Forest Harvesting 
Council, AW.J. Sinclair, Manager of Western Division of the Forest Engineering Research Institute of Canada, 
W.J. Watt, Research Pedologist, Cariboo Forest Region, BCFS and Larry Price, Resource Officer, 
Planning/Inventory, Golden Forest District, BCFS, for their interest in this research work and for supplying the 
necessary color aerial photographs for this study. Financial support of the British Columbia Interior Forest 
Harvesting Council toward the research for this study is greatly appreciated. 
7.0 REFERENCES 
Curran, M. and S. Thompson. 1990. Measuring soil disturbance following timber harvesting. British Columbia 
Ministry of Forests, Victoria, B.C. (In preparation), 16 p. 
Krag, R.K. and S.R. Webb. 1987. Cariboo Lake logging trials: a study of three harvesting systems on steep 
slopes in the Central Interior of British Columbia. Forest Engineering Research Institute of Canada, 
Tech. Rep. TR-76, 48p. 
Lee, Y.J. 1990. Computer digitization of large scale aerial photography and digital image analysis for assessing 
soil disturbance on clearcuts. In Remote Sensing for Resource Inventory, Planning and Monitoring, 
Proceedings of the Third Forest Service Remote Sensing Applications Conference, Tucson Arizona, 
U.S.A 9-13 April, 1990. USFS, Amer. Soc. Photogram. Eng. and Rem. Sens. 4 p. (In press). 
Lewis, T. and W.W. Carr. 1989. Developing timber harvesting prescriptions to minimize site degradation - 
Interior sites. Land Management Handbook Field Guide Insert. Timber Harvesting Subcommittee, 
Interpretation Working Group, British Columbia Interior Forest Harvesting Council. British Columbia 
Ministry of Forests, Victoria, B.C. 26 p.