Productivity, costs, and optimal spacing of skyline corridors of two cable yarding systems in partial cutting of second-growth forests of coastal British Columbia

• Main Author: Rutherford, Dag
• Language: English
• Published: 2009
• Online Access: http://hdl.handle.net/2429/4425

Public pressure to end clearcut logging, and changing forest management needs have increased opportunities for partial cutting in British Columbia's second-growth coastal forests. Production economics and engineering design of cable harvesting systems for partial cutting in second-growth forests of British Columbia (BC) are largely unknown. Scientific research and working experience in partial cutting forest harvesting operations in coastal areas of the Pacific Northwest of North America is from the United States or from selection harvesting of old growth forests in coastal BC prior to 1935. Time and motion studies were conducted in fall of the 1992 and spring of 1993 on two cable yarders in second growth coastal forests (on Vancouver Island) of BC. The goals of the studies were to design a forest engineering system for field layout of cable harvesting systems in partial cutting, develop production and cost models for the two yarders , compare the productivity and costs of partial cutting and clearcutting, and develop models for optimal spacing of skyline yarding corridors. Results showed that forest engineering of partial cutting with cable yarders was dependent upon corridor spacing and tailspar tree location, size and species. Production and cost analyses showed that wider corridors and larger crew sizes were more efficient, but also that productivity gains from larger crew sizes did not result in lower operating costs. Clearcutting in all instances was shown to be more efficient and cost effective than partial cutting. The coastal stumpage appraisal system was shown to vastly under-estimate the added costs of partial cutting in relation to clearcutting. Optimal skyline corridor analysis and comparisons demonstrated that lower variable yarding costs resulted from wider corridor spacing, both contractors spaced yarding corridors narrower than optimal, and costs could be reduced by optimal spacing of corridors. The quantity of timber harvested with partial cutting is increasing annually, and knowledge and experience in these harvesting systems is necessary and will be an asset.