." .~ ~' Productivity and cost of manual felling f< 1 f:.I and cable skidding in central Appalachian hardwood forests Jingxin Wang* Charlie Long Joe McNeel John Baumgras chainsaw and skidding with a cable Abstract skidder. Time studies showed that hour- A field production stlldy was conducted for a manual harvesting system using a ly felling production increased while chainsaw and cable skidder in a central Appalachian hardwood forest site. A partial cut skidding productivity decreased from was performed on a 50-acre tract with an average slope of25 percent. Felling time per the treatments 45 percent, to-60 percent, tree was most affected by diameter at breast height and the distance between harvested and to 75 percent of residual stocking. trees while skidding cycle time was mainly affected by turn payload size and skidding Regression equations were later devel- distance. Productivity of chainsaw felling was 362 ft.3 per productive machine hour oped based on the above time-study data (pMH) (2.23 thousand board feet [MBF]/PMH) with a wlit cost of$8.0/cunit (100 cu- (Brock et a1. 1986), which can be used bic feet) ($13.0/MBF). Cable skidding productivity was 289 ft.3/pMH (1.78 MBF/ for estimating production rates and costs PMH) and unit cost was $27.0/cunit ($50.0/MBF). The balanced manual harvesting for similar thimling operations. system could produce 7,236 ft.3 per week (44.63 MBF/week) with unit cost of Howard (1987) took a different ap- $37.0/cunit ($60.0/MBF). proach to estimating timber harvesting production and cost with cable skidders by collecting shift-level data on fuel consumption, repairs, maintenance, different machine and harvest prescrip- and other operating costs and combined GenerallY the more mechanized the tions. Jones (1983) conducted a time that with telephone survey data. The harvesting system, the more productive it study on a 60-acre tract with three thin- model developed was based on these is. However, as mechanization of harvest- ning treatments in northern West Vir- costs and previous detailed production ing increases, operational costs also in- ginia. The three treatments were defmed studies to categorize the effect of tim- crease (Blinn et a1. 1986). Mechanized as 45 percent, 60 percent, and 75 percent ber size and species 011logging costs harvesting also causes additional site dis- of the residual stocking. The harvest and profitability. Howard found that turbance and residual stand damage (Mar- comprised of manual felling with a tree size had the greatest effect on skid- tin 1988). Due to the higher initial cost of mechanized harvesting machines, larger diameters and crowns of hardwoods, and The authors are, respectively, Assistant Professor, Fo=er Research Assistant, and Direc- the relatively steep terrain in central Ap- tor, West Virginia Univ., Division of Forestry, 322 Percival Hall, PO Box 6125, Morgantown, palachia, manual harvesting with chain- WV 26506-6125; and Project Leader, USDA Forest Serv., Northeastem Research Station, saw felling and a ground-based cable Morgantown, WV 26505. The authors thank Mr. JeffSlahor for his valuable comment on an earlier draft of this manuscript, the USDA Forest Servo Northeastern Research Station for skidder is still the most commonly used funding this project, and TrusJoist MacMillan and MeadWestvaco for allowing observation system in the region. of their logging contractors. This paper was received for publication in June 2003. Article No. 9699. Few previous studies addressed the *Forest Products Society Member. production and cost of harvesting cen- ~Forest Products Society 2004. tral Appalachian hardwood stands wlder Forest Prod. J. 54(12):45-51. FOREST PRODUCTS JOURNAL VOL. 54, No. 12 45 1; .~ j ding costs and species only affected Methods and data (DBH) (inches), and merchantable costs in felling. Howard stated that the The manual harvesting system exam- height (feet). There was only one tree results could be used to establish con- ined consisted of felling with a chainsaw being cut per cycle for chainsaw felling. Order and location of felled trees were tract rates and merchantability rates and skidding with a cable skidder. Fell- based on stand characteristics. ing was perfonned using a Husqvarna noted so that species, DBH, and mer- chantable height of the trees could be re- Production analysis of thuming hard- 372 chainsaw with SA-horsepower (hp) corded when felling was complete. wood was conducted using small tractors engine and bar length ono inches while Functions of the cable skidder were instead of larger ground-based skidders skidding was done using a TimbeIjack defined as: (Huyler and LeDoux 1991). The produc- 460 cable skidder with an engine of 174 tivity and cost of five small tractors were hp. The field study was conducted trom 1. Travel empty: Begins when the identified and compared using a com- July to September of 2002 on Mead- skidder leaves the the landing with an puter progran1. The study reported that Westvaco timberland in Randolph empty cable. Ends when the skidder small-scale harvesting machines are fea- County, West Virginia. The site contain- arrives at the felled stems to be ex- sible but type of machine, careful site se- ed most hardwood species common to tracted. lection, and layout are critical to ensuring the central Appalachian region but was 2. ChoIce:Begins when the skidderoper- a profitable operation. Compared to predominantly made up of six species: ator gets out to choke the felled stems. larger equipment, these small tractors northern red oak (Quercus rubra), black Ends when tl1e skidder is full and were more suitable and economic in thin- birch (Betula lenta), red maple (Acer ready to travel back to the landing. ning of small stands with less soil com- rubrum), sugar maple (Acer saccha- 3. Travel loaded: Begins when the paction and less residual stand damage. rum), American basswood (Tilia ameri- skidder starts toward the landing full Some production/cost studies using cana), and chestnut oak (Quercus of felled stems. Ends when the skid- manual harvesting systems have been prinus). The slope on this site ranged der reaches the landing with the conducted in harvesting planted pine tram 10 to 45 percent with an average of stems. stands in the south. Kluender and Stokes approximately 25 percent. The type of 4. Unchoke: Begins when the skidder (1994, 1996) conducted a time study on harvest on this site was a partial cut of marked trees. The initial stand density operator gets out to unchoke felled a southern pine harvest consisting of stems. Ends when the skidder leaves manual felling, grapple skidding, and was about 250 trees per acre and the re- moval was 3.6 thousand board feet the landing for another load. cable skidding. The harvest method Stems were bucked with a bucksaw ranged tram clearcutting to single-tree (MBF) per acre. A handheld computer loaded with the on the landing after skidding. The vari- selection and the proportion of basal ables recorded for the cable skidder are area removed was used to measure har- Windows CE-based time study data log- travel distance trom landing to stump vest intensity. Lortz et al. (1997) con- ger was used to record elemental times (feet), nu111-b.erof felled stems per turn, ducted further analysis of southern pine and other harvesting related factors tree species, butt diameter (inches), and felling with chainsaws and produced (Wang et al. 2003). When the handheld computer could not be used, times and merchantable length (feet) for each indi- several equations for estimating felling vidual felled stem. times and productivity. Kluender et al. operational variables were measured us- (1997) found that grapple skidders ing a stopwatch and recorded on paper. A total of 300 cycles for chainsaw "were consistently faster and more pro- A work cycle for each operation con- felling and 150 cycles for cable skidding ductive than cable skidders." Their re- sisted of certain elemental functions and were observed in the field. The number sults also indicate that harvest intensity factors. The times for each function and of observations varied depending on the affects grapple skidding productivity but the value of each factor were recorded in amount of time required collecting time not cable skidding productivity. This the field. Elemental time functions for study data. Each felled tree or stem skid- ded was measured for DBH/butt diame- was explained by the fact that the cable chainsaw felling were defined as: ter to the nearest inch and merchantable skidder had to approach every stem indi- 1. Walk to tree: Begins when the feller vidually while the grapple skidder could starts toward the tree to be cut. Ends height/length to the nearest one-half log grab several logs each time. The study when the feller reaches the tree. or 8 feet. Local volume equations were used to compute the volume of felled found that grapple skidding productivity 2. Acquire: Begins when the feller starts stayed the same, while cable skidding trees or skidded stems (Wiant 1986, clearing around the tree and judges Relli1ie 1996). became more productive. where the tree will fall. Ends when The objectives of this study were to: the feller is ready to cut the tree. Statistical Analysis Systems (SAS@) was used to analyze the data. The gen- 1. conduct a contu1Uous time study on 3. Cut: Begins when the feller starts erallinear model (GLM) was employed manual harvesting systems with a cutting the edge of the tree. Ends to detennine if any differences of ele- chainsaw and a cable skidder in cen- when the tree hits the ground. mental times, cycle time, and hourly tral Appalachian hardwood forest, 4. Top/delimb: Begins when the feller productivity existed an10ng operational 2. estimate the production rates and starts delimbing the tree.