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This study evaluated precommercial, full-tree thinning of saplings and small poletimber (1-8 inches dbh) using chainsaws and modified farm tractors for skidders. To facilitate cutting large numbers of small trees (1-5 inches), the chainsaw was fitted with a felling frame. The cutter felled and manually bunched up to 145 trees/ 2.7 tons per productive man- hour. Average production, assuming 73% efficiency, was 90 trees/1.8 tons per scheduled hour at a cost of $6.22/ton. Skidding was done by a two-wheel drive grapple skidder and a four-wheel drive farm tractor with double-drum winch. The grapple skidder produced 3.8 tons per scheduled hour at a cost of $8.25 per ton, assuming a 75% utilization rate. The cable skidder produced 4 tons per scheduled hour at a cost of $7.00/ton; preset chokers increased production to 4.7 tons/hour at a cost of $5.96. The key to production was a modified herringbone pattern of corridors which facilitated skidder access to the wood. The weakest link in the operation was the difficult, labor-intensive work of felling and bunching.
Maine Agricultural and Forest Experiment Station
stand characteristics, spruce-fir forests, pre-commercial, full-tree thinning
Hoffman, Benjamin F. Jr.. 1986. B813: Harvesting Small Trees for Biomass. Maine Agricultural and Forest Experiment Station Bulletins 813.