Operational Trials of Cut-To-Length Harvesting of Poplar in a Mixed Wood Stand

Cut-to-length harvesting systems offer an alternative to conventional mechanical systems for thinning mixedwood stands. We evaluated the performance of a single-grip harvester and forwarder in a poplar-dominated mixedwood stand in Southern Ontario to quantify the ef-fect of tree size and tree form on harvester productivity and harvesting cost, and to assess the damage caused by the harvesting operation to advance regeneration and re-sidual trees. A single-tree selection silvicultural system was used. Individual trees were assigned a form index based on their visual estimates of limb size and stem form. The cut-to-length harvester produced 23.1 m3 per produc-tive machine hour (PMH). Forwarder productivity was 17.2 m3/PMH. The results indicate a significant and positive relationship between harvester productivity and tree size (dbh) and tree form. Tree size (dbh) has the greatest influ-ence on the unit cost of harvesting. At an average 27 cm dbh and extraction distance of 200 m, the stump-to-land-ing cost was approximately 10 US$/m3. As tree size in-creased, the unit cost of wood produced decreased. Dam-age to residual trees and advance regeneration was mini-mal. The results suggest that single-grip cut-to-length harvesting systems can be effective in managing poplar-dominated mixedwood stands