ANNOTATION: Presents a comparative study of three systems used for thinning pine plantations and mixed conifer stands. Whole-tree methods; Cut-to-length systems; Hybrid systems. All three produced small sawlogs and fuel chips. Time-motion data were collected to predict cost per unit volume. ABSTRACT: 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 processor, loader, and chipper. The cut-to-length system included a harvester, forwarder, loader, and chipper. A hybrid system combined a feller buncher, harvester, skidders, loader, and chipper. Time-motion study data were analyzed to predict cost per unit volume. The cut-to-length system had higher costs and yielded less fuel than the other systems. In plantations, the hybrid system was least expensive, while the whole-tree system was cheaper in the natural stands. The harvesters were capable of handling larger trees in the natural stands, and could remove 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 study.