Production rates and costs of cable yarding wood residue from clearcut units

Calculations were made of the incremental production rates and costs for yarding and loading logging residue in clearcut old-growth Douglas fir/western hemlock forests in western Oregon. Three different cable yarding machines were used in various configurations: highlead, shotgun skyline (Flyer), running skyline, and skyline with haulback. Regression equations were developed for productive yarding time as a function of slope yarding distance, number of merchantable logs per turn and residue volume per turn. Average yarding production rate for turns containing both merchantable logs and residue was 1832 cubic feet per hectare at a cost of $0.18/cubic foot. Results show that residue was most efficiently yarded (and is close to costs of merchantable logs) when a turn contains 1-3 pieces of residue, totalling at least 15-20 cubic feet.