Alternative Skid Trail Retirement Options for Steep Terrain Logging

Transcription

1 2001 Counil on Forest Engineering (COFE) Conferene Proeedings: Appalahian Hardwoods: Managing Change Alternative Skid Trail Retirement Options for Steep Terrain Logging Mathew F. Smidt Assistant Professor and Extension Speialist, Forest Operations, Shool of Forestry and Wildlife Sienes, 108 M.W. Smith Hall, Auburn University, Randall K. Kolka Assistant Professor, Forest Hydrology, Department of Forestry, University of Kentuky, 125 Cooper Building, Lexington, KY ABSTRACT In winter trials of deep tillage and reontouring of skid trails were implemented on three sites in northeastern Kentuky, USA to examine their potential as skid trail retirement options. While effetive, urrent Best Management Praties (BMPs) for trail retirement do not address two potential benefits of retirement: reovery of normal hill slope hydrology and amelioration of soil ompation. Subsoiling and reontouring both signifiantly redued soil ompation ompared to the ontrol. Preliminary data from runoff sampling indiated none of the treatments were similar to the undisturbed hillside, but reontoured treatments had surfae runoff 77% of the ontrol and sediment yield 41% of the ontrol. Subsoil treatments results for sediment yield and runoff volume were between the ontrol and reontour treatments. Prodution levels from researh appliation of deep tillage showed that the ost ould be ompetitive with onventional BMPs. The reontouring treatment was three to five times the ost of onventional BMPs. General appliation of deep tillage and site-speifi appliation of reontouring may be ost neutral or redue net ost of BMPs if treatments inrease tree growth or signifiantly improve water quality. INTRODUCTION In the Appalahians, ground-based logging on the steep terrain results in a network of bladed trails on hillsides. These trails are a primary soure of erosion and ommonly over from 10-25% of the harvest area (Stuart and Carr 1991; Miller and Sirois 1986; Kohenderfer 1977). The Best Management Praties (BMPs) for trail retirement following the harvest are installation of ross drainage and establishment of vegetative over. There are two limitations to onventional BMPs: 1) the areas with soil damage (erosion, ompation, destrution of surfae soil) ontinue to aumulate with suessive stand entries and 2) the trails disrupt the normal hillslope surfae and subsurfae water flow leading to inreased long-term erosion and potential hanges in watershed hydrology. Addressing these limitations, may provide opportunities for alternative methods for trail retirement inluding the restoration of the hillslope to the original profile or deep tillage of the trail running surfae. While a traked exavator was the obvious hoie for reovery of the fill slope, hoies for deep tillage of the trail surfae are varied (Andrus and Froehlih 1983). The goals for tillage on these trails inlude: 1) ameliorate soil ompation, 2) inrease infiltration, 3) enhane germination and growth of ground over and tree growth, 4) avoid aeleration of erosion through trail surfae disturbane, and 5) maintain or enhane trail surfae drainage. The entire study was designed to evaluate seedling growth and soil water, surfae water and sediment movement aross the profile of trails treated with water bars and revegetation (ontrol), reontouring and revegetation (reontour), and subsoiling and revegetation (subsoil). Here we report on the implementation of the reontouring and subsoiling, soil onditions immediately following implementation, and preliminary data from water volume and quality measurements. METHODS The researh sites were loated in northeastern Kentuky, USA in the Cumberland Plateau Physiographi Provine. The Cumberland Plateau is haraterized by short, steep sloped hills with relatively narrow ridges. The area is generally onsidered part of the Appalahian region. Two of the sites, Moore Branh and Road Branh were within 3 miles of the other and had similar soil texture (sandy loam). The Fuller Branh site was about 25 miles away and had loamy soils. For subsoiling appliations we hose the Tilth Self-Drafting Winged Subsoiler (subsoiler). Charateristis of the subsoiler were desribed by Andrus and Froehlih (1983), and its appliation was desribed in Andrus and Froehlih (1983), Davis (1990), De Long et al. (1990) and Hogervorst and Adams (1994). Trials of the subsoiler were ompleted on trail segments on side hills and ridge tops on the three researh sites. The prime mover or trator was a Caterpillar D6R XL. University of Kentuky staff operated the trator with the subsoiler. The operator was an experiened trator operator

2 Slope (N-mm -1 ) 2001 Counil on Forest Engineering (COFE) Conferene Proeedings: Appalahian Hardwoods: Managing Change but had no previous experiene with the subsoiler. The manufaturer provided support for subsoiler operation during the study. The subsoiling was ompleted in early Deember 1999 about one week after 25-mm of rainfall. Light rain fell (12- mm) after the ompletion of the Fuller Branh Site and before starting operations on the Road Branh and Moore Branh sites. Soils were dry in spite of the rain sine extreme drought onditions prevailed for the area throughout the summer and fall We hired a loal ontrator with a Caterpillar E120B to omplete the fill slope reovery and re-ontour on setions of side slope roads. Reontouring ourred during moist soil onditions in late February We took ontinuous timing measurements on the subsoiler from video reordings. The exavator was videotaped on three of the six trail setions. To maintain a omplete randomized blok design for the experiment, the exavator walked over the subsoiled plots to get to the reontour plots. The exavator ompated surfae soil in subsoiled treatments about 3-m under the trak. Srap lumber was plaed every m perpendiular to the trail to distribute the weight of the exavator more evenly aross the trail. Soil was ompated about 7-10-m under the lumber. Following the appliation of the treatments we took penetrometer readings in the inner trak, middle, and outer trak loations at three systemati loations in the treated plot. Readings were taken with a Rimik reording penetrometer with a 130-mm 2 one aording to ASEA Standard: ASAE S313.2 (ASAE 1989). Slopes of the resistane profiles were omputed using ordinary least squares. In some ontrol loations the penetrometer ould not be inserted beause the soil strength exeeded the apaity of the penetrometer. For those loations we estimated the slope using a regression developed from bulk density, soil moisture, and lay ontent (R 2 =0.29). The slopes were modeled using ANOVA with a omplete randomized blok design. In Spring 2000 we planted eah of the treatments with 20 eastern white pine and 20 tulip poplar bareroot (1-0) seedlings. For three treatments on eah site and an undisturbed referene loation we installed TDR probes for soil moisture data above the trail, on the trail surfae, and below the trail and runoff olletion plots on the trail surfae. Runoff data presented here were olleted from June to August RESULTS Soil Reontour and subsoil treatments were signifiant in reduing soil strength on the trail running surfae (P=0.0001). Reontour and subsoil treatments were signifiantly different from the ontrol (P<0.05), but the reontour treatment was not signifiantly different from subsoil treatments. Figure 1 shows the mean slopes for eah of the sites and treatments. The ontrol on the Fuller Branh site was signifiantly less ompat than the other two ontrols. Water and sediment Preliminary analyses revealed that the reontour treatments had the lowest volume runoff and the lowest sediment runoff (Table 1). None of the treatments were similar to the undisturbed hillslope (referene) b a a Fuller Branh Moore Branh Road Branh Control Reontour Subsoiled Figure 1. Slopes of the penetrometer profile for ontrol, reontour, and subsoiled treatments for eah site. Letters represent signifiant differenes at P<0.05. Table 1. Summary of preliminary runoff and sediment data. Letters indiate signifiant diffenes at P<0.05. Runoff volume (L m -2 ) Sediment (g m -2 ) Subsoil 8.5 a ab Reontour 5.9 b b Control 7.6 ab a Referene Prodution The timing data for the subsoiled trail setions are presented in Table 2. Delay times were large due in part to an inexperiened operator. Most frequently delays were aused when the operator tried to avoid reating soil disturbane and to avoid damaging standing trees. Some delays were produed when the operator attempted to minimize damage

3 2001 Counil on Forest Engineering (COFE) Conferene Proeedings: Appalahian Hardwoods: Managing Change to the subsoiler and minimize disturbane by not moving large roks with the subsoiler. Delays for maneuvering, avoiding stumps, and debris omprised over 78% of the total produtive delay time. The operator often reeived instrution about how to deal these problems inreasing the length of the delay. Travel time to the loation was not inluded in the subsoiling data sine a) we were using the dolly mounted onfiguration whih required baking down some trails and b) mahine speed was redued to minimize damage to the experimental plots prior to treatment. Delay free prodution ranged from 0.59 to 2.31 km-hr -1 and prodution inluding produtive delays only ranged from 0.42 to 1.75 km-hr -1 (Table 3). A treatment width of 4-m (the width of the trail running surfae) yielded prodution with produtive delays ha-hr -1. For ridges and benhes the atual treated width ould be up to 50% wider (Andrus and Froehlih 1983). Table 2. Subsoiler prodution and delay times (seonds) for eah site and trail segment Site Road Moore Fuller Trail segment Length (m) Produtive time (se) Delay (se) Stump Tree Debris Rok Maneuver Waterbar Other Total Table 3. Subsoiler prodution estimates and mean prodution in kilometers per hour and hetares per hour for eah trail segment. Site Trail seg. Length (m) Prodution Prodution (delay (produtive free) delays) Km-hr -1 Ha-hr -1 Km-hr -1 Ha-hr -1 Road Road Road Road Moore Moore Fuller Fuller Fuller Mean The reontouring treatments took from 18 to 25 minutes for eah 25-m plot. No signifiant delays were experiened during the ompletion of any of the six plots. The ontrator we employed indiated that his prodution inluding travel out would be 0.1-km-hr -1 on sites similar to the researh sites. Using the same 4-m width for the trail surfae yielded prodution rate of 0.04 ha-hr -1. Using the distane from the inside of the ut slope to base of the fill slope (6-m), the prodution inreases to 0.06 ha-hr -1. The loal ontrator rate for this size mahine was about $120 per hour yielding a ost of $1200 per kilometer of trail or $3000 per hetare (4-m wide trail). DISCUSSION Both treatments signifiantly redued ompation. Reontouring had an advantage in this regard sine the penetrometer sampled an upper layer of the soil profile. In the subsoil and ontrol treatments the penetrometer sampled subsoil that was at least 0.5-m below the original soil surfae. The result was onsiderably higher rok ontent in addition to penetrometer resistane. In addition the penetrometer results of the subsoil treatments were probably affeted by exavator traffi following the subsoil treatment. The importane of the differenes won t be known until tree growth, infiltration, and runoff data are olleted from these treatments. Reorded prodution of the subsoiler was slower than prodution speeds previously reorded beause the operator had only one day of training prior to the trial and was relying on instrutions from the manufaturer and the researhers. Using one pass to lear slash and the seond pass to subsoil De Long et al. (1990) reorded prodution of 0.29 ha-hr -1. The most reent published osts are from Davis (1990) of $160 per hour for both rawler trator and subsoiler. Delong et al. (1990) predited ownership and operating osts for the subsoiler at $5.88 (Canadian) per hour. Subsoiler osts may differ slightly in the Appalahians due to operator profiieny and loal terrain and soil onditions. Loal ontrator rates for a 180 Hp rawler trator at the time of the study ranged from $150 to $200 per mahine hour. Rates quoted to us may have been inflated beause ontrators did not have a good sense of how the trator would be used and the amount of downtime that would be experiened. In De Long et al. (1990) the first pass was used to lear slash from the subsoiled areas and took 60% of the produtive time. Total produtivity would be sensitive to slash over on the trails. In the Appalahians fellers and

4 2001 Counil on Forest Engineering (COFE) Conferene Proeedings: Appalahian Hardwoods: Managing Change skidders ombined have onsiderable ontrol over how muh slash is on the trails following harvest. Using a rate of $175 hr -1 for the prime mover and subsoiler, the average produtivity of subsoiling from this study (0.35-ha-hr -1 ), and a first pass that onsumes 0.5-ha-hr -1, the treatment ost equals $850-ha -1. Doubling the produtivity of the subsoiling but with the slash removal prodution at 0.5-hahr -1 dereases osts to $600-ha -1. While muh of the value of these two tehniques has yet to be determined by tree growth and runoff results, the osts estimated are not that different from present retirement osts. Assuming that 1 water bar would be installed every 18-m whih relates to an average trail slope of 15% (Stringer et al. 1997), the ost of reontouring equals onventional retirement at $21.60 per waterbar. At the low (0.17-ha-hr -1 ) and high (0.70-ha-hr -1 ) produtivity levels from the subsoiler (0.50-ha-hr -1 for the first pass), the ost of subsoiling equals onventional retirement at $9.92 and $4.31 per waterbar, respetively. From survey results Shaffer et al. (1998) found average waterbar osts at $15 eah. A prodution study gave the ost per water bar at this density $3.34 per waterbar (Hewitt et al. 1998). The ability to put a larger dozer on the harvest for tillage should have prodution benefits in all phases of retirement. Most loggers that have dozers have smaller dozers sine their primary funtion is bunhing and skidding and not earth moving. In addition the ost of assigning a produtive mahine to a retirement task is probably somewhat higher than the mahine rate or even the ontrator rate for a omparably sized dozer. Both reontouring and subsoiling are likely to inrease the suess of revegetation through seedbed preparation and may allow inreased mehanization of seeding, mulhing, and fertilizing through equipping the prime mover with bulk spreaders. A limiting fator for both reontouring and subsoiling would be the area treated at one loation. Small harvests with only a few hetares to treat would drive up the osts per hetare beause of transport osts and poor mahine utilization. Current investments in trail retirement through BMPs may represent an under investment in retirement to ameliorate soil damage or planning to redue area impated. Stewart et al. (1988) showed that several methods used to derease the ompated area in harvests of forests in the Paifi Northwest, inluding tillage, yielded positive returns. In hardwood forests our understanding of the growth losses due to trails is extremely limited and suh a omparison would be diffiult. Adding the ost of amelioration to the ost of ground-based harvesting in this steep terrain likely represents the true opportunity for aerial logging systems or other ground-based systems that minimize trail density and trail slope. AKNOWLEDGEMENTS This study was made possible by grants from the U.S. Forest Servie Southern Researh Station, University of Kentuky College of Agriulture, Kentuky Water Resoures Institute, and E.O. Robinson Trust. We also like to thank Auburn University, the Daniel Boone National Forest, Ed and Susan Fields of Tilth, In., Mead Paper: Fine Paper Division, University of Kentuky Cooperative Extension Servie, and Whayne Supply, In., for their ontributions. REFERENCES Andrus, C.W. and H.A. Froehlih An evaluation of four implements used to till ompated forest soils in the Paifi Northwest. For. Res. Lab., Oregon State Univ., Res. Bull pp. ASAE Agriultural Engineers Yearbook of Standards. ASAE, St. Joseph, MI. Davis, S Effetiveness of a winged subsoiler in ameliorating a ompated layey forest soil. W. J. App. For. 5(4): De Long, D.L., P.M. Osberg, C. Clarke, and W. Hays Trial of the Tilth winged subsoiler working in naturally ompat soils in north British Columbia. FERIC Teh. Note, TN pp. Hewitt, D., N. Huyler, P. Hannah, and C.LeDoux Determining time as a ost in onstruting waterbars on forest sites in Vermont. In: Pro. Counil on Forest Engineering Meeting, July Hogervorst, J.B. and P.W. Adams Soil ompation from ground based thinning and effets of subsequent skid trail tillage in a douglas fir stand. In: Pro. Soil, tree, mahine interations in forest operations workshop, FAO/ECE/ILO Forsitrisk Working Group and IUFRO Working Group P , Feldafing, Germany. Kohenderfer, J.N Area in skidroads, truk roads and landings in the entral Appalahians. J. For. 75: Miller, J.H. and Sirois, D.L Soil disturbane by skyline vs. skidding in a loamy hill forest. Soil Si. So. Am. J. 50: Shaffer, R.M., H.L. Haney, Jr., E.G. Worrell, and W.M. Aust Forestry BMP implementation osts for Virginia. Ford. Prod. J. 48(9): Stewart, R., H. Froehih, and E. Olson Soil ompation: an eonomi model. W. J. App. For. 3(1):20-22.

5 2001 Counil on Forest Engineering (COFE) Conferene Proeedings: Appalahian Hardwoods: Managing Change Stringer, J., L Lowe, M.F. Smidt, and C. Perkins Field guide to best management praties for timber harvesting in Kentuky. Univ. of KY., Coop. Ext. Serv., Dept. of For. FOR-69. Stuart, W.B. and J.L. Carr Harvesting impats on steep slopes in Virginia. USDA Gen. Teh. Rep. NE-148, pp