Abstract

A mechanized harvesting system consisting of a feller-buncher and grapple skidder was examined in four central Appalachian hardwood sites. Diameter at breast height (DBH) of felled trees averaged 16.12 inches and ranged from 7 to 31 inches. The number of logs skidded per turn was between 1 and 7 with an average turn payload of approximately 85 ft.[.sup.3]. Hourly production of feller-buncher felling was 1,267 ft.[.sup.3] per productive machine hour (PMH) or 7.81 thousand board feet (MBF) in Doyle scale per PMH with a unit cost of $8 per 100 cubic feet (cunit) ($12.97/MBF) while grapple skidding productivity was 512 ft.[.sup.3]/PMH (3.16 MBF/PMH) with a unit cost of $16/cunit ($25.93/MBF). Productivity of topping/delimbing with chainsaws after feller-buncher felling was 726 ft.[.sup.3]/PMH (4.48 MBF/PMH) with a unit cost of $4/cunit ($6.48/MBF). The mechanized harvesting system could produce 28,678 ft.[.sup.3] per week (176.89 MBF/week) and the unit cost was $29/cunit ($47/MBF). Results indicated that the higher initial capital investment of mechanized harvesting system could be paid off by its higher hourly production.

**********

Although manual felling with a chainsaw and skidding with a ground-based cable skidder is the most commonly used harvesting system in the central Appalachian hardwood region, the need for increased production and safety has loggers looking at alternatives such as a feller-buncher and grapple skidder system. Mechanized harvesting systems using feller-bunchers and grapple skidders have been commonly used in the southern United States for years, but use is increasing in the northeast. In the south, harvesting operations have moved quickly to complete mechanization with highly productive equipment in the past 30 years (Greene and Corley 1996). As a result of that trend, sawhead feller-bunchers and grapple skidders have become standard equipment on many southern harvesting operations (Greene and McNeel 1991, Greene and Corley 1996).

Many researchers have addressed the production and cost of feller-bunchers and grapple skidders in harvesting southern stands. Greene and McNeel (1987) investigated the productivity, costs, and butt log damage in clear-cutting southern pine. Using computer simulation, Greene et al. (1987) also addressed stand and operating effects on feller-buncher productivity in second thinnings of southern pine. Greene and McNeel (1991) examined the productivity and cost of three different types of sawheads (chain-and-bar, intermittent-disk, and continuous-disk) used on feller-bunchers in the south. They found that continuous-disk sawheads were the fastest, followed closely by intermittent-disk, and chain-and-bar sawheads. Move-and-sever time equations were developed for feller-bunchers using each type of sawhead. Even though continuous-disk sawheads were fastest, Greene and McNeel (1991) suggested using intermittent or chain-and-bar saw-heads when operating in large timber or on rock or steep terrain due to the fact that the continuous disk might cause considerable damage in these areas.

Productivities of grapple skidders were investigated in extracting full southern pine trees (Tufts et al. 1988). They reported that the principal variables affecting skidding cycle time were skidding distance, machine flywheel horsepower, number of bunches grappled, and number of trees per turn. Lanford and Stokes (1996) compared two harvesting systems--a feller-buncher/grapple skidder system and a harvester/forwarder...