COMPARISON OF MECHANIZED SYSTEMS FOR THINNING PONDEROSA PINE AND MIXED-CONIFER STANDS

Three systems for thinning pine plantations and naturally-regenerated stands were studied. All three produced small sawlogs and fuel chips. The whole-tree system consisted of a feller buncher, skidder, stroke p rocessor, loader, and chipper. The cut-to-length system included a har vester, forwarder, loader, and chipper. A hybrid system combined a fel ler buncher, harvester, skidders, loader, and chipper. Time-motion stu dy data were analyzed to predict cost per unit volume. The cut-to-leng th system had higher costs and yielded less fuel than the other system s. Ln plantations, the hybrid system was least expensive, while the wh ole-tree system was cheaper in the natural stands. The harvesters were capable of handling larger trees in the natural stands, and could rem ove limbs from the plantation pines, up to a limit. The cut-to-length system could operate on the steep and broken terrain included in the s tudy.