Abstract

Three harvesting systems of chainsaw/cable skidder, feller-buncher/grapple skidder, and harvester/forwarder were simulated in harvesting three hardwood stands 30 to 50 years old in central Appalachia. Stands were generated by using a 3D stand generator. Harvesting prescriptions included clearcut, shelterwood cut, selective cut, diameter limit cut, and crop tree release cut. The interactions among stands, harvest prescriptions, and harvesting systems were evaluated statistically in terms of production, cost, and traffic intensity. The weekly production of the chainsaw/cable skidder system was 5,773 [ft.sup.3] (163 [m.sup.3]) with a unit cost of $38 per 100 cubic feet (cunit) ($13.4/[m.sup.3]). The feller-buncher/grapple skidder and harvester/forwarder systems could produce 22,153 [ft.sup.3] (627 [m.sup.3]), and 8,423 [ft.sup.3] (239 [m.sup.3]) with the unit cost of $34.3/cunit ($12/[m.sup.3]) and $46.8/cunit ($17/[m.sup.3]), respectively. Results indicated that the feller-buncher/grapple skidder system was the most productive and cost-effective system for harvesting small-diameter hardwood stands in central Appalachia under the simulated harvesting prescriptions. Compared to harvesting mature stands, harvesting small-diameter hardwood stands was about 15 percent (felling) and 14 percent (extraction) less productive, and 29 percent (felling) and 13 percent (extraction) more expensive. Results should help planners, loggers, and foresters efficiently manage and utilize small-diameter materials in the region.

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Harvesting small-diameter stands of high densities is of interest to forest products companies, loggers, and landowners in central Appalachia in order to reduce fuel loading and improve residual stand health and timber utilization. However, harvesting such stands is usually more labor intensive and not cost-effective due to the small piece size processed and the non-merchantable products harvested. LeVan-Green and Livingston (2001) reported that average cost for thinning small-diameter and underutilized material is approximately $70 per ton while traditional markets for thinned material can only pay approximately $25 per ton for energy and $35 per ton for chips. Additionally, the efficiency of harvesting equipment could be lowered and the residual stand might be potentially damaged while partial cutting or thinning small-diameter stands.

Productivity and economic feasibility of thinning or partial cutting has been studied by many researchers in different regions. Wagner et al. (2000) found that harvesting sawtimber of less than 9 inches diameter at breast height (DBH) could not cover harvest and delivery costs, and the removal of sawtimber of less than 7.5 inches DBH had a negative return in the western United States. Combining data from previous field studies, Hartsough et al. (2001) examined six harvesting systems and developed cost models to estimate the costs of harvesting small-diameter trees of natural stands in the interior Northwest. They indicated that the models could be appropriate for long-term stand management plans but the gaps in the data and differences in the study conditions might limit the accuracy and potential applications. Han et al. (2004) reported that forest harvesting systems, road accessibility, hauling distance to manufacturing facilities, and market price of thinning materials were the major factors affecting economic feasibility of small-wood harvesting and utilization. By computing tree volume and potential product recovery, they evaluated the economic feasibility of an integrated harvesting system for harvesting...