Thinning Productivity and Cost for a Mechanized Cut-to-Length System in the Northwest Pacific Coast Region of the USA

A production study of a single-grip harvester and forwarder was conducted in a second-growth thinning operation in western Oregon, USA. Production levels for the harvester exceeded 30 m3/ PMH (productive machine hour, delay-free). There was no significant difference in harvester production between stands marked prior to logging and those in which the trees were selected by the operator. Production levels for the forwarder ranged from 10.2 m3 to 14.5 m3/PMH. When landing space was limited, a two-pass forwarding technique (separate loads of sawlogs and pulpwood) was more productive than a single-pass technique (products mixed on each load and sorted at the landing). Regression equations were developed to predict harvester production per PMH on the basis of tree dbh and to predict forwarder production per PMH on the basis of product type, volume per load, and travel distance. Thinning cost for this cut-to-length system wasUS$12.49/m3 [US$35.37/c unit],excluding hauling and a profit-and-risk allowance.