Felling and Skidding Costs ~ssociated with Thinning a Commercial Appalachian Hardwood Stand in Northern West Virginia1

Transcription

1 Felling nd Skidding Costs ~ssocited with Thinning Commercil Applchin Hrdwood Stnd in Northern est Virgini1 Smuel M. Brock nd Kenneth D. Jones, Division of Forest y, est Virgini University, Morgntown, V 2656, nd Gry. Miller, USDA Forest Service, Northestern Forest Experiment Sttion, P.O. Box 44, Prsons, V ABSTRACT. Detiled cost informtion on thinning opertions is needed to develop economic guidelines for mnging immture centrl Applchin hrdwood stnds. Three thinning tretments were pplied in 5yrold mixedok, cove hrdwood stnd in northern est Virgini. A commercil logging contrctor using chin sws nd rubbertired skidder conducted the logging opertions. Timestudy dt were used to compute production rtes for felling mrked trees nd skidding treelength h s to rodside lndings for ech thinning tretment. Production rtes rnged from 2.7 to 3. cunitslhr depending on the residul stocking tretment. The cost of merchntble mteril t rodside rnged from $1.79 to $11.99 per cunit. Regression equtions for predicting felling nd skidding times were developed for ech tretment. Dt from these equtions cn be used in estimting production rtes nd costs for similr thinning opertions. A nomogrm is provided for estimting felling nd skidding costs for 6% residul stocking tretment, the current recommended silviculturl prescription for stnds similr to the study re. North. 1. Appl. For , Dec Thinning immture hrdwood stnds pre&nts n opportunity for incresing the size nd qulity of future hrdwood timber supplies (USDA For. Serv. 1982). Such increses re needed to meet expected increses in ' This study ws supported in prt by the USDA Forest Service, Northestern Forest Experiment Sttion, Prsons, V, under Coopertive Agreement No Published with the pprovl of the Director of the est Virgini Agriculturl nd Forestry Experiment Sttion s Scientific Article demnd. To evlute thinning lterntives, forest mngers nd lndowners need relible cost dt for rnge of thinning intensities. This pper compres felling nd skidding costs ssocited with three thinning tretments pplied in commercil Applchin hrdwood stnd. Equtions re presented for predicting felling nd skidding times, nd nomogrm is provided for estimting production costs. The 6c study re is locted on the est Virgini University Forest in northern est Virgini. Treted stnds were previously unmnged nd pproximtely 5 yr old. Site index, bse ge 5, ws 9 for yellowpoplr nd 8 for northern red ok, the 2 most common species. STUDY METHODS The study re ws divided into twenty 3c experimentl units. Ech experimentl unit ws ssigned t rndom to one of four tretments: thinning to 75%, 6%, or 45% residul stocking, or unthinned (control). During the summer of 1982, cut trees were selected to provide the desired residul stocking on ech unit. The uplnd hrdwood guide ws used to mesure residul stnd stocking (Gingrich 1967). A permnent.5c growth plot ws estblished within ech 3c experimentl unit, leving 2.5c exterior buffer zone. The growth plots were inventoried (ll trees 1. in dbh nd lrger) before logging, nd residul trees were tgged to provide future growth dt relting to ech tretment. hile the initil stnds were uniformly overstocked (Tble ), the stocking guide used overestimtes percent stocking for stnds hving significnt component of such species s yellowpoplr. Yellowpoplr ccounted for 41% of the merchntble cubic foot volume in the initil stnd, nd blck cherry ccounted for n dditionl 12%. Red ok comprised 15% of merchntble volume; other oks, 18%; nd miscellneous hrdwoods the remining 14%. Although yellowpoplr ws mjor component of the initil stnd, it ws of lesser importnce compred to ok in the residul stnd. Oks ccounted for 18% of the volume removed nd 48% of the residul volume. Merchntble volume in cubic feet (wood only) ws clculted to minimum top dimeter of 8. in inside brk using the model developed by Kozk nd others (1969) nd dpted to Applchin hrdwoods by Mrtin (1981). Bord foot volume ws estimted with the nterntionl Min log rule nd form clss 78 volume tbles Logging Site nd System The study ws conducted t n elevtion of 21 ft on slopes not exceeding 23%. A truck rod.5 mi in length ws constructed to provide ccess from pved highwy to the study site. Approximtely 2.25 mi of skid rod were constructed within the site. Logging ws done in the spring of 1983, under reltively wet conditions. Merchntble timber ws purchsed nd removed by commercil logging contrctor. Two experienced crews, ech using chin sws nd John Deere 54B rubbertired skidder, conducted the thinning opertion. Ech crew consisted of feller nd skidder opertor. Up to five chokers per hitch were used in skidding (Fig. 1). Time Studies Timestudy dt were collected for both logging crews; ech crew ws observed nd timed independently Times were recorded for two ctivities: treefelling nd logskidding. Productive felling time included wlking to the tree, swmping, ctul cutting, limbing nd topping, nd bucking Delys included refueling nd shrpening the sw, witing for the skidder, cutting trees below the limit of merchntbility (7.6 in dbh), coffee breks, nd personl time. Productive skidding time included trveling unloded from the deck to the woods, choking logs, winching logs, moving to secure dditionl logs, trveling loded bck to the deck, unhooking, nd some bucking on the deck. Delys included winching stoppges, trffic jms with other hevy equipment, equipment mintennce, witing for topping or bucking, coffee breks, nd personl time. NJAF 3(1986) 159

2 Tble 1. Chrcteristics of the initil, cut, nd residul stnds for the three thlnnlng levels on the est Virgini University Forest, Sternslc Bsl relc (ft2) Stocking (%) Merchntble volurne/c stocking in 1.O in 1.O in tretment (%) Stnd in dbh nd lrger in dbh nd lrger in dbh nd lrger Cubic foot Bord foot 75 nitil 6 nitil 45 nitil Only trees 11.6 in dbh nd lrger were included in the bordfoot volume. For both felling nd skidding, productive time nd dely time elements were mesured to the nerest.1 min by stopwtch. The totl time for felling or skidding cycle ws determined by summing the individul elements. The volume produced in cycle ws determined from tree or log mesurements recorded during the hme study. Timestudy dt re summrized in Tble 2. RESULTS A regression eqution ws developed for ech thinning tretment to predict productive felling time per tree s function of merchntble cubic foot volume per tree (Tble 3). Thinning tretment nd volume per tree were sttisticlly significnt t the 5% level. Other mesured vribles, including species, dbh, initil stnd stocking, initil bsl re per cre, nd rtio of the number of hrvested trees to the totl number of trees per cre, were not significnt. Dely time ws not included in the dependent vrible, time (minutes) per tree, becuse most felling delys were relted to the system s whole rther thn to the individul tree. For skidding, regression eqution ws developed for ech tretment to predict skidding time s function of three significnt independent vribles: number of logs per turn, onewy skidding distnce, nd cubic foot volume per turn (Tble 4). Other vri bles, including verge slope, percent slope greter thn or equl to 12%, nd the product of lod nd slope were not significnt. The dependent vrible, time (minutes) per skid turn, included productive time nd ll delys except crew breks, personl time, etc. These ctivities resulted in nonproductive time tht ws not relted to individul skid turns. The three equtions were solved using lest squres nlysis with the following sttistics: R2 ws.66; the stndrd error of regression ws 2.95; nd the Frtio ws 36. Production Rtes The regression equtions were used to predict felling nd skidding production time in ech tretment. Predicted times were bsed on selected vlues for the independent vribles. Felling production time ws predicted using the verge volume per tree computed from the mrked cut in ech tretment. Skidding production time ws predicted using 4 logs per turn, onewy skidding distnce of 6 ft, nd the men volume per turn observed in the time study. These vlues were selected to represent the verge conditions in the study re nd to provide bsis for compring the tretments (Tble 5). Volume figures used in the equtions were combined with the predicted cycle times to compute production rte estimtes for felling nd skidding in cunits (1 ft3) per hour using the formul: volume per cycle (fp) P = predicted cycle time (min) 6 minlhr X 1 ft3/cunit Fig. 1. An verge of four treelength logs were removed in ech skidding cycle. where P = production rte in cunits per hour, excluding ll delys nd nonproductive time for felling nd excluding nonproductive time only for skidding. Delys were ccounted for using djustment fctors determined from 16 NJAF 3(1986)

3 Tble 2. Summry of timestudy dt for three thinning levels, est Virgini University Forest, Merchntble stocking Number of Productive Totl volume Opertion tretment (%) observtions time (hr) time (hr) ~roduced (ft3) Felling , , ,21 Skidding , , Tble 3. Felling time e~utions nd regression sttistics for three thinning levels. Stndrd Percent error of stocking R regression Frtio Felling time equtions Y = X X Y = X +.53 Xb Y = X.162 X Y = productive felling time in minutes per tree, excluding delys nd nonproductive time. X = Merchntble cubicfoot volume per tree. Coefficient of X is not significnt t 5% level. the time study dt in ech tretment. For felling, the djustment fctor ws.5, indicting tht predicted cycle time is 5% of totl cycle time. This reltionship between productive felling time nd totl felling time lso ws found in previous studies (Srles et l. 1984, Miyt 198). For skidding, the djustment fctor ws.91, indicting tht predicted cycle time is 91% of totl cycle time. This fctor ccounted for nonproductive time (coffee breks, etc.) not included in the predicted skidding time per turn. The sme dlustment fctor ws used for ech tretment to mke direct comprisons of the predicted cycle times nd production rtes (Tble 5). n ll tretments, the skidding opertion ws the "wek link in the logging systemtht prt of the system with lowest output per hour (Bumgrs nd Mrtin 1978). The wek link determines the production rte of the entire system nd provides bsis for computing the cost per unit of production for ll system components combined. For exmple, the estimted production rte for felling in the 6% residul stocking tretment ws 3.2 cunits (1 fp of wood only) per hour (Tble 5). For skidding, theestimted production rte ws 3 cunits per hour. n combintion, the two system components re limited by the lower production rte of the skidding opertion. Thus, production of merchntble volume t the lnding in the 6% tretment ws 3. cunits per hour. Estimted production in the 75% nd 45% tretments ws 2.7 nd 3. cunits per hour, respectively (Tble 5). Production Costs Costs were determined by dividing the production rte of the system's wek link into the cost per hour for ll system components combined (Tble 6). n this study, felling, bucking, nd skidding costs totlled $32.36 per hour. ges were ssumed to be $7. per hour plus 28% mndtory fringe benefits for Socil Security, orkmn's Compenstion, nd Unemployment nsurnce. Mchine costs were estimted using cost fctors (Miyt 198) nd the,mnufcturer's recommended mintennce schedule for the equipment used. The totl lbor nd mchine cost ws $1.13 per hour for felling nd $22.23 per hour for skidding. Bucking ws done in the woods or t the lnding, depending on the circumstnces. Thus, these hourly costs include bucking. Using these cost estimtes nd the production rtes determined from th6 regression equtions, the combined cost of felling, bucking, nd skidding showed moderte differences mong the tretments (Tble 6). DSCUSSON Tble 4. Skidding time regression coefficients for three thinning levels. The regression equtions developed Regression coefficients in this study provided bsis for computing logging costs from stump to Regression 75 % 6% 45' log deck for three thinning tretterms stocking stocking ments. hile felling, bucking, nd ntercept (b,) ~ ~ " skidding costs re importnt, totl Number of logs per lod (b,) = logging costs lso include the costs of Skidding distnce (b,) loding, huling, nd rod construc Size of lod in merchntble ft3 (b,) '5646 tion. Thus, the results of this study re Not significnt t 5% level; intercept significnt t 6% level. useful for predicting only portion of Tble 5. Estimted felling nd skidding production rtes for three thinning levels, est Virgini University Forest, Selected vribles used in equtions Estimtede Dely production stocking Number of Onewy Volume per Predicted time djustment rte Opertion tretment logs distnce (ft) cycle (ft3) per cycle (min) fctor (cunitslhr) Felling = 1.36C Skidding b 14.43d Men volume per tree computed from the mrked cut. Men volume per cycle observed in the time study. Predicted felling time per tree includes productive time only. Predicted skidding time per turn includes productive time nd ll delys except crew breks, personl time, etc. ft3 per cycle 6 minlhr Production rte = A x dely djustment fctor. minlcycle 1 ft31cunit NJAF 3(1986) 161

4 Tble 6. Comprison of production rtes nd costs for three thinning tretments. Totl lborb Felling, b~cking,~ nd mchine nd skidding stocking Production rte cost cost tretment (%) (cunitslhr) ($lhr) ($/cunit) Bsed on skidding production. ncludes wges for two crew members plus mchine costs for wheeled skidder nd chin sw. Bucking ws done by the feller or on the deck depending on the circumstnces. totl logging costs ssocited with viculturl prescription for stnds simthinning opertions. ilr to the study re (Gingrich 1967). The 6% residul stocking tret The other tretments were pplied to ment is the current recommended sil determine the effect of different thin ning intensities on hrvesting costs Estimted costs in the 6 nd 45% residul stocking tretments were equl under the conditions studied. One reson for this is the similrity in the volume removed per skid turn. The verge volume ws 81 ft3 per turn in the 6% tretment nd 83 f13 per turn in the 45% tretment. Even though the tretments differed with respect to residul stocking, the mrked cut in merchntble trees (7.6 in dbh nd lrger) ws similr. The number of merchntble trees removed differed by only 3 trees per cre. Averge volume per tree ws higher in the 45% tretment, but due to occsionl PRODUCTON RATE CUNTSSCHEDULED HOUR CUBC FOOT VOLUMETURN (4 LOGSTURN) NONPRODUCTVE TME 7 1 ADJUSTMENT FACTOR J X Y r... CO t z 2 ONEAY SKDDNG DSTANCE 25 Q f z u J 2 u k : (ia 15 rn TOTAL LABOR AND MACHNE COST (SSCHEDULED HOUR) lo D 5 Estimted cost is 9.51CUNT. Fig. 2. Smple grphicl computtion of felling, bucking, nd skidding cost in 5yrold Applchin hrdwood stnd thinned to 6% residul stocking. 162 NJAF 3(1986)

5 bucking in the woods, verge volume per skid turn ws not incresed ccordingly. n the 75% tretment, the estimted cost of merchntble volume t the lnding ws $1.2 more per cunit thn in the hevier thinning tretments. Volume per skid turn ws 7.3 ft3, bout 11 ft3 less thn in the recommended tretment. To increse verge turn volume nd lower costs, the crew could hve incresed the lod from 4 to 5 ogs per turn. This djustment in skidding strtegy increses the estimted production rte from 2.7 to 3.1 cunits per hour. The regression equtions cn be used to evlute similr djustments in ll tretments. To illustrte the procedure for estimting felling, bucking, nd skidding costs for the 6% residul stocking tretment, nomogrm is provided (Fig. 2). The nomogrm is grphicl representtion of the three bsic steps required to compute the cost of merchntble mteril t the lnding. Loding, huling, nd rod construction re not included. The first grph in Fig. 2, upper right, determines the production rte in cunits per hour, excluding coffee breks, personl time, nd other nonproductive time. This grph ws derived from the skidding time eqution for the 6% residul stocking tretment. Since skidding ws the wek link in the logging system, production rtes nd costs re determined by the skidding opertion. Production rtes were computed for three skidding distnces nd rnge of verge turn volumes, while the verge number of logs ws held constnt t 4 logs per turn. To determine the production rte, enter the first grph (upper right) t the pproprite verge turn volume nd drw verticl line down to the pproprite skidding distnce. At this point (A), the production rte, excluding nonproductive time, is found t the left. n this exmple, the estimted production rte for 81 ft3 per turn in 4 logs per turn nd skidding distnce of 5 ft is 3.5 cunits per hour. The second grph in Fig. 2, upper left, computes the production rte per scheduled hour by ccounting for nonproductive time. This grph includes three djustment fctor lines to llow for rnge in crew efficiency. To ccount for nonproductive time, move horizontlly from point A to the left, stopping t the pproprite djustment fctor line. At this point (B), the production rte per scheduled hour, including ll delys nd nonproductive time, is red t the bottom. n this exmple, the dely djustment fctor is.9 nd the estimted production rte per scheduled hour is 3.2 cunits. The third grph in Fig. 2, lower left, computes the cost per cunit from the production rte per scheduled hour nd the totl lbor nd mchine cost (for both felling nd skidding) per hour. Becuse lbor nd mchine costs cn vry, four cost curves re provided. To compute felling nd skidding costs per cunit, drw verticl line from point B down to the pproprite cost curve. At this point (C), the predicted cost per cunit is found t the right. n this exmple, costs were ssumed to be $3 per hour nd the predicted cost is $9.5 per cunit, point D. f solved lgebriclly, the predicted cost is $9.41 per cunit. Merchntble volume from ll 45 treted cres sold for $13,264. The totl yield from ll tretments combined ws 77 cunits. The verge yield ws 17.1 cunits per cre, similr to the verge yield in the 6% residul stocking tretment, 18.3 cunits per cre. Bsed on the verge stumpge price observed in this sle, i.e., $17.23 per cunit, the 6% tretment would provide revenue equl to $315 per cre. So even in smll trct of immture timber, there is n opportunity for owners to undertke commercil thinnings, thereby leving their timber in more productive condition for future ernings. LTERATURE CTED BAUMGRAS, J. E., AND A. J. MARTN The wek link logging systems nlyzer. USDA For. Sew. Gen. Tech. Rep. NE4. 63 p. GNGRCH, S. F Mesuring nd evluting stocking nd stnd density in uplnd hrdwood forests in the centrl sttes. For. Sci 13:3853. KOAK, A., D. D. MUNRO, AND J. H. G. SMTH Tper functions nd their ppliction in forest inventory. For. Chron. 45: MARTN, A. J Tper nd volume equtions for selected Applchin hrdwood species USDA For. Sew. Res. Pp. NE p. MYATA, E. S Determining fixed nd operting costs of logging equipment. USDA For Serv. Gen. Tech. Rep. NC p. SARLES, R. L., J. L. ARTLUFF, AND K. R. ~ E NACK Chinsw felling in hrdwood thinnings. n Hrvesting the South's smll trees. Proc For. Prod. Res. Soc. Conf. USDA FOR. SERV An nlysis of the timber sitution in the United Sttes, USDA For. Sew. For. Resour. Rep. 23, sh., DC. 499 p. NJAF 3(1986) 163