Conventional and mechanized logging compared for Ozark hardwood forest thinning: productivity, economics, and environmental impact

Replicate 4-ac plots in a 70-year-old upland oak forest on slopes averaging 30 percent in southeastern Missouri were harvested by conventional (chainsaw + skidder) and mechanized (small tracked skid steer + feller-buncher and harvester + forwarder) logging equipment. The heavy thinning prescribed by a crop tree management approach removed an average of 1,300 ft(3) or 40 tons per acre of pole wood and sawlogs, leaving an average basal area of 36 ft(2)/ac. The harvester/forwarder was the most productive (ft(3)/production hour), and the small feller-buncher the least, being the only system whose (unreplicated) production cost exceeded revenue. Production costs (excluding mobilization, overhead, and profit) of the conventional and harvester/forwarder systems were not statistically different on average, but the lowest cost of the latter was 14% less than that of the conventional system. The frequency of residual trees experiencing substantial bole damage was not significantly different among logging technologies, but the harvester/forwarder did have a higher incidence of substantial crown damage. The area of exposed mineral soil did not differ significantly among technologies, and soil compaction sufficient to impede rooting was rare. Lack of site and operator replication and incomplete cost analyses over a limited time prohibit generalization of these conclusions.