Cut-to-length harvesting of short-rotation eucalyptus

Traditional whole-tree harvesting systems work well in short-rotation hardw ood plantations, but other methods are needed where it is desirable to leav e the residues on the site. We tested a system consisting of a cut-to-lengt h harvester, forwarder, mobile chipper, and chip screen to clearcut a 7-yea r-old plantation of Eucalyptus viminalis. Three levels of debarking effort by the harvester (minimal, partial, and full), and two levels of screening (with and without) were evaluated. The harvester had the lowest production rate and highest cost of the system elements. Harvester production rate was strongly affected by tree size and somewhat by debarking level. Bark conte nts for full debarking averaged 1.5 percent; screening apparently did not r educe bark content any further. Estimated stump-to-truck costs (without scr eening) for the system in stands of good form varied from $19 per bone dry ton (BDT) for 11-inch DBH trees to $72/BDT for 3-inch trees. For trees in t he 5- to 11-inch range, and an average forwarding distance of 500 feet, a b alanced system would include three harvesters, two forwarders, and one chip per. The system may be cost competitive with whole-tree systems.