Effects of alternative silvicultural treatments on cable harvesting productivity and cost in western Washington

Increasingly, alternative silvicultural methods have been considered to meet the demand for nontimber values such as visual quality and biodiversity in the Pacific Northwest. The successful implementation of these alternative silviculture treatments requires careful consideration of economics and operational efficiencies in timber harvesting. This study used detailed time study and shift-level data to assess the effect of alternative silvicultural treatments on the production and cost of cable harvesting in western Washington. Four silvicultural treatments were examined: clearcut, two-age, patch cut and thin, and group selection. Servicultural treatments greatly affected the production and cost of timber harvesting, especially in felling and yarding processes. The average yarding cycle time (3.74 minutes/cy(le) in the clearcut unit was shorter than those in other partial cutting treatment units because there were no residual trees to work around and higher harvest volumes per acre, compared with the partial cut units. The average tree size greatly affected yarding cost: the clearcut unit had the second-highest yarding cost ($52.38/thousand board feet [mbf]) because of the smallest piece size (69.6 board feet/piece). Stump-to-truck cost for this study ranged from $70.49/mbf for the patch cut and thin to $120.19/mbf for the group selection. Carriage types and yarding direction also had an impact on yarding productivity.