Sveriges lantbruksuniversitet

Institutionen för skogsteknik

Uppsatser och Resultat nr 277 • 1995

FOREST HARVESTING SYSTEMS FRIENDLY

TO THE ENVIRONMENT

I wan Wästerlund and Awatif E. Hassan

The Swedish University of Agricultural SciencesDepartment of Operational EfficiencyS-776 98 Garpenberg

ISSN 0282-2377

ISRNSUI-ST-UPPRLT--277-- .SE

MASTER DISTRIBUTION OF THIS DOCUMENT IS UNLIMITED

Preface

The present report was presented at the 1994 ASAE Winter Meeting, Atlanta,

Georgia, U.S.A. Since ASAE does not publish any proceedings, I decided to publish

it as a Research Note at the Department of Operational Efficiency, Swedish

University of Agricultural Sciences, Garpenberg, to increase the accessability.

Iwan Wästerlund

Professor

Paper No. 947512An ASAE Meeting Presentation

FOREST HARVESTING SYSTEMS FRIENDLY TO THE

ENVIRONMENT

by

Iwan Wästerlund, Assoc. Prof. Awatif E. Hassan, Prof.Swed. Univ. Agric. Sci. Col. of Forest Resources,S-776 98 Garpenberg North Carolina State Univ.,

Sweden Raleigh 27695-8002, USA

Written for presentation at the1994 ASAE Winter Meeting

Sponsored byASAE

Atlanta Hilton & TowersAtlanta, GA,

December 13-16, 1994

Summary:The trend in forestry practices today in Europe and USA in general, and Scandinavian countries inparticular is towards adapting systems based on landscape planning. Thus common harvestingequipment available on the market will have to be replaced to meet these though demands.Environmentalists recommend that wood fiber should be harvested either by selection cutting orcommercial thinning thus leaving the site "undisturbed" with no sign of machine traffic. This mandate willpreserve ground water quality and assist in soil conservation. However, to meet the pulp and paper aswell as saw mill industries, demand for wood from this method of cutting (selective or commercialthinning), requires a thorough examination of our harvesting systems and techniques. This paper willdiscuss present and future machines that are friendly to the environment. Hypothetical designs andimprovements of existing machine systems will be addressed and recommendations will be made forfuture research activities.

Keywords:Harvesting, ecosystem, machine systems.

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Forest harvesting systems friendly to theenvironment

Abstract

Introduction

Silvicultural practices meeting environmental concerns

Silvicultural strategies

Potential methods of cutting in the Ecology Management (EM)

Requirements for a friendly operationa. System requirementsb. Road and terrain requirementsc. Space/clearance requirementsd. Handling requirementse. Acceptable degree of damagef. Environmentally friendlyg. Cost efficiency

Existing machine systemsI. HarvestingII. Extraction

III. Combined methods

Evaluation of existing machine systems

Conceptual designs for the future

Conclusions

References

FOREST HARVESTING SYSTEMS FRIENDLY TO THEENVIRONMENT1

Iwan Wästerlund and Awatif E. Hassan2 3

AbstractThe trend in foresty practices today in Europe and U.S.A. in general and Scandinavian countriesin particular, is towards adapting systems based on landscape planning. Thus commonharvesting equipment available on the market will have to be replaced to meet these toughdemands. Environmentalists recommend that wood fiber should be harvested either by selectioncutting or commercial thinning thus leaving the site "undisturbed" with no sign of machine traffic.This mandate will preserve ground water quality and assist in soil conservation. However, tomeet the pulp and paper as well as saw mill industries demand for wood from this method ofcutting (selection or commercial thinning), requires a thorough examination of our harvestingsystems and techniques. This paper will discuss present and future machines that are friendlyto the environment. Hypothetical designs and improvements of existing machine systems willbe addressed and recommendations will be made for future research activities.

INTRODUCTION

Forest machines are often developed on a trial-and-error basis to meet theindustry need for forest operations. When the need for a certain task arises,design modifications of machine systems from the construction industry areadapted. Through that process, there are plenty of machine systems availablefor most forest operations and in particular for clearcutting. However, the useof efficient machinery for harvesting operations may be accomplished bychanges in forestry practices towards sustainable forest silviculture and environ-mentally friendly systems. Thus, future machine systems for forestry operationsmight look quite different from the present ones, but the main task for treecutting and extraction will remain the same.

A number of harvesting system reviews have been conducted but with noevaluation of alternative systems that take into consideration the "new"silvicultural practices (cf. Jackson & Stokes, 1990; Reisinger & Aust, 1990). Amore useful approach would be to examine the forestry operations, environ-

1 Paper No. 94-7512 presented at the 1994 ASAE International Winter Meeting, Atlanta, GeorgiaUSA.

2The authors are, Iwan Wästerlund, assoc. prof., Swedish University of Agricultural Sciences, S-77698 Garpenberg, Sweden, and Awatif E. Hassan, professor, North Carolina State University, Dept. ofForestry, Raleigh, N.C.

3 The use of trade names in this article does not imply endorsement by the North CarolinaAgricultural Research Service of the products named, nor criticism of similar products not mentioned.

mental requirements, existing machine systems, and future wood demand. Thus,the main objectives of this paper are to:(1) Define environmentally friendly operational systems,(2) Examine and evaluate existing machine systems that meet the above

definitions, and(3) Recommend design modifications of existing systems and present new

hypothetical concepts of future machines that are friendly to the environment.

SILVICULTURAL PRACTICES MEETING ENVIRONMENTAL CONCERNS

The pressure from environmentalists, politicians and the public about natureimpose constraints on how we perform the harvesting operations as well as thesilvicultural regimes. Treatment of the forest is considered to be a public issuewhereas agricultural fields are the farmers' private business (Smith, 1978). It isalso ironic that silviculture has been directed towards agricultural type ofcultivation at the same time that minimum-tillage agriculture begins to appearas a mean of soil conservation. A new trend is that it has become fashionableto use recycabte mateiial such as wood but at the same time it has becomemore difficult to get allowances to cut trees! The most recent "green" dogmain Europe is that we should only use wood fibers coming from non-clearfelledareas for paper products because clearcutting is unnatural and destroys theenvironment. Recycling of paper is promoted but how many times can the woodfiber be recycled?

A number of federal laws affect the forest management on private forest landsand a number of best management practices have been developed (Cubbage,1993). The extent of these voluntary regulations on operational methods mayincrease in the future. The management of the national forestlands is moredirected for a sustainable yield of several goods including water, wildlife, timber,recreation, and range. Biodiversity and sustainability are keywords for forestmanagement all over the world and they are generally agreed upon (WCED,1987) but still the practical interpretations are missing (Smith, 1993). Sustainabili-ty is defined by the Brundtland commission as a development that "meets theneeds of the present without compromising the ability of future generations tomeet their own needs" (WCED, 1987). The genemhpAtac has at present a very"romantic" view of the forest and want it to be "as Wfc» old days" but what doesJt mean? Should the forest look like it was yesterday or as it was 500 years ago?

also not commonly recognized that the forest change appearance with ageand if left alone, the dying and fallen trees may look unattractive to the public.

Endangered species do often depend on old trees. They are endangered simplybecause the appropriate stands are getting more rare. On the other hand, evenif spotted owls or woodpeck«R»would not need old-growth, the public still wants

large trees. The existence of the "natural" forest itself is fundamental in thepublic concern. Schroeder and Daniel (1981) tried to find out an estimation ofscenic beauty and big ponderosa pines got high scores whereas dead trees,slash, and small sized trees got negative scores. Here are conflicts with bothtraditional forestry as well as biodiversity. However, a stand with seed trees,young ingrowth and no dead standing trees could get rather high scores froma scenic beauty point of view and not be in conflict with an adapted forestryregime (Fig.1). Furthermore, it should be emphasized that not all forests shouldbe old-growth since a number of species may gain by the access to differentstages of the forest development.

The objective is thus to have a balance between production, biodiversity andmultiple use. The means are to have gocd silvicultural strategies.

250 T

200-

5 150'c3Ulco 100-

50-

Young for Old for Shelter Selfregen

Figure 1. Scenic beauty estimates (SBE) according to formulas given bySchroeder and Daniel (1981) for appearance of young forest, old forest,shelterwood and self-regeneration.

Silvicultural Strategies

There are a number of options for the silvicultural regimes and some are morelikely to happen in the future. McQuillan (1994) suggested three forms ofregimes (1) Old-growth left untouched, (2) Ecosystem management with bothwood yield and multiple-use, and (3) tree farms. Boyce & McNab (1994) argued

that the forestry regimes should be scheduled on a landscape level to producethe desired diversity, thus the above mentioned ecosystem management mustbe planned for large areas.

Ecosystem management will probably need a "shift in silvicultural paradigm"(O'Hara et al., 1994). A silviculture to meet the requirements for biodiversity andmultiple-use should include mixed species, two-aged and multicohort standstructures produced with flexibility and landscape perspectives and also meetthe nontimber objectives with a small sacrifice of timber production (O'Hara etal., 1994). According to Holland et al. (1994) good harvest levels can becompatible with maintenance of diversity but the net values may be reduced.

Another aspect is the need for good timber quality that partially has beensacrificed on behalf of maximized wood production (Bragg et al., 1994).Improvement of the timber quality by growing denser stand, may outweigh thereductions in net values when the market appreciate these qualities. Theharvesting costs may have to increase for such systems but on f 9 other handit may be balanced by the reduced regeneration costs.

A scarce supply of high-value products could justify wide application of selectionmanagement (Seymour et al., 1976). To emphasize the growth of high qualitysawlogs and veneer that yield high stumpage returns can work together withmanagement objectives such as aesthetic values or protection against landslides(Smith, 1978).

reased concern about erosion, leaching, and sedimentation problems may»nefit other systems than clearcutting not necessarily only on sensitive sites

(cf. Cromack et al., 1978). According to Switser et al. (1978) the intensity of sitedisturbance varies initially among reproduction methods in the order: clearcut> seed trees > shelterwood > selection. A similar ranking between the methodsis also given by Stone et al. (1978) when considering water yield and flow,nutrient loss, stream temperatures, and reduction in surface soil organic matter.Although a loss of nutrients or organic matter may not impact growth of treesin some areas (Allen et al., 1991).

In summary, in the future it is likely to exist a change towards more diversesilvicultural regime practice. In some areas, the forest will be left more or lessuntouched as old-growth for different reasons. Here no harvesting operationswill be done. In other areas, the tree farm concept w>M b*4|£.most suitableregime and here the maximum production goal can be fulfilled» a general fiberresource. The tree farms may have a hamMtkig system similar to presentpractices and the concept for machine and systems development will mainly beas rationalization. Based on ownership, Switzer et al. (1978) estimated thatabout 20-25 % of the forest land will be managed intensively in the South of

U.S.A. This practice will leave about one third to half of the forested land to bepotentially comitted to some kind of ecology management (EM). Do we haveproper harvesting sysiems for the s.lvicultural regimes in these areas? Thequestion first to be answered is what selection modes do we have and theanswer determines what operations to be done.

Potential Methods of Cutting in the Ecology Management (EM)

Clearcutting, cutting of small patches or openings might be one of thealternatives in the future, especially for regeneration of shade intolerantspecies. Opening up the area could be necessary to start up a degeneratedsite. In principle, the commonly used equipment for ordinary clearfelling canbe used. A technical problem might, however, raise as these areas wouldbe small, which means that the machinery should be easy to move to nextcutting place. Also, the clearing of small sized trees that have to be removedto prevent undesired ingrowth, might reduce machine productivity comparedto conventional operations. Other cutting systems are (Seymour et al., 1S86;Megalos, 1994):

Seed-tree selection: renewal of the stand by self-sowing from remainingselected seed-trees, which are left for that purpose and are thus rather few(80-120 trees per ha).

Shelterwood: a stand left after cutting denser than for seed trees (150-250trees per ha). Best for species that need partial shade and for protection ofthe young growth to sudden climatic changes.

One-cut shelterwood: the removal of the overstory in a single operation andreleasing advance growth without prior seed cuttings.

Two-aged cut (irregular shelterwood): part of the overstory left in place untilnext rotation.

Improvement cutting: early thinning to upgrade stand quality with control ofstocking and removal of poor-quality trees and use of the harvested treesas fuelwood or chipped for pulp; mainly in hardwoods.

Single tree selection: deliberates creation and maintainance of a balanced all-aged stand (Seymour et al., 1986) giving the stand a more natural,undisturbed appearance. The uneven-aged stand structures are typicallydefined in terms of basal area, maximum diameter, and others (Murphy &Shelton, 1994). The stand should have trees with a reverse J-shapeddiameter structure where a maintenance can be made by a diameter-limitcut. Desired basal area for loblolly pines is 14-18 rrrVha with maximum 40cm dbh. This method can only be used for tolerant species.

Group-tree selection: cutting of a group of trees and creating larger openingsthan with single-tree selection.

Precommercial thinning: precommerctat work to alter the composition anddensity of the stand.

8

An important step in the the silvicultural prescriptions is the identification ofdifferent sites and fitting the species composition to them (Smith, 1978). In theEM landscape, a number of different silvicultural regimes will be practiced andsome of them can be done easily with present logging machinery and equipmentlike the seed-tree selection. However, with the one-cut shelterwood type, thedamage levels of the residual stand (both aesthetic and quality) might be high(Bragg et al., 1994) and destruction of advance growth by logging system shouldbe avoided (Seymour et al., 1986). The more moving around the remainingtrees, the more damage will occur and the risk increases with increasing treesizes and remaining basal area (Ostrofsky et al., 1986).

According to Seymour etal. (1986), increased mechanization has made loggingoperations required by shelterwood cutting more difficult. However, the primaryadvantage of selective thinning over systematic row thinning is a larger, better,and potentially more profitable residual stand. Properly designed and managedselective thinning is cost competitive with row thinning (Stokes & Lanford, 1982).Another aspect is that it is most unlikely that we are going back to heavy labourintensive forestry work and the main issue must be to design proper mechanizedoperations suitable for EM; efficient machine system with minimum traffic andsoil disturbance. In some areas, the harvesting system used should reduce andutilize the slash to prevent forest fires (cf. Covington & Moore, 1994).

Requirements for a Friendly Operation

The job to be done is thus a selection harvesting ranging from early conventionalselective thinning (i.e. thinning from below) to single-tree selection management,primarily designed for working with smaiUimber holdings for private landowners.Preferably the system and machinery should be suitable for that broad rangeof operations to avoid heavy traffic associated with single function mMbines.

A. System requirements.* The harvestinjjsystem could be shortwood, log length, or tree length without

particular restriction. Tree chipping could be considered. Fulltree harvestmight be restricted due to environmental considerations. Big slash pilesshould be avoided.

* The system set up should be easy to move and install on next operatingplace since the cutting areas might be small.

* The system must require a smalt taMcfing area since many operation sitesmight be involved. With a 2 % landing area, a small clearcut on one hectarshould be limited to 200 m2 landing area but preferably less than that.

* The mechanization level of the harvesting system should be more than 90

B. Road and terrain requirements.* The forest road network might have to be spaced and only second class

roads may consitute 50 % of the main access roads, which would imply longextraction distances. The space for landings might also be a limiting factor.

* The temporary roads should be winding to minimize the look of being man-made and access trails should be within normal tree spacing. Thisrequirement might restrict the use of ground-based tree-length extraction dueto its space demand when operating on curves.

' The harvesting system should be able to work on different ground conditionsfrom hard to soft (e.g. wetlands), uneven terrain, and inclination up to 50 %.More severe terrain would require different systems. This requirement wouldfavour wheeled machinery unless working on very wet sites and/or verysteep terrain.

o o o . O 0 • °• 0 * 0 *

o • o 0 .0 • O

0 • . o •• . o ° •

o • . o . o .o . o o . o

• • ° • • . , •0 • O • O • ° Ä O

O • q *3 ?m

Figure 2. A forest stand showing tree distribution. Only the marked trees (black)should be removed in selection cutting.

C. Space/clearance requirements.* A selective tree removal is the aim and hence, the system should be able

to work without any forced cut of the selected trees, thus working within theselected tree spacing (Fig.2).

* The density of the stand aftar the operation might vary between 1200 - 350trees per ha, which gives a general spacing between the trees from 2.9x2.9

10

m to 5.3x5.3 meter. This density might not be a common strategy for coastalloblolly plantations with about 500 - 700 trees per ha after first thinning(Greene & Stokes, 1989; Rummer, 1993), but these plantations might beconsidered as the tree farm type of forestry.

* The total width of the forest machine could then be maximum 2.5 - 3 m withat least 0.4 m on each side to minimize stem and root damage (O'Connor,1991). However, for highway transportation, the maximum width may berestricted to 2.4 m.

P. Handling requirements.* The system should be designed to handle up to almost the biggest trees.

With cutting from above or a diameter-limit thinning, the machine should beable to handle trees up to 60 cm dbh, which means single trees of a totalmass of 4,500 kg (Fig.3).

* Trees should be sawn off and not sheared to reduce damage to the butt log(Gallagher, 1984, and Stokes & McNeel, 1990).

33 3027

Tree height, meter

Figure 3. Estimates of living tree mass a& Allen (1994) and Zobel et at. (1972).

to formulas given by Rodriguez

E. Acceptable degree of damage.* The machine system should be designed to limit damage to the remaining

trees. Decay resulting from butt damage not only decrease the present value

11

of the trees, but also affect the growth rate of the trees in addition to thespread of the rot within the tree (Whitney, 1991). An EM stand will most likelyhave longer rotations times than optimal for fiber production and then buttdamage will be more costly. Entries in the stand might be done in 10-20 yearintervals.

* Traffic should be reduced to a minimum (max. 20 % area trafficked) as toavoid rutting, root damage, and soil disturbance. In these EM stands, therewould be rather small possibilities to repair soil damage such as sitepreparation or ripping, since the stand is depending on natural regeneration.However, there are situations where enrichment plantating could be desiredto adjust species composition, improve the genetic qualities).

* Damage to young trees within the stand should be as little as possible. Treeskidding should therefore be avoided.

* To avoid soil compaction with ground-based machinery, the nominal groundpressure should be below 60 kPa and the machine mass should be below10 tonne (Wästerlund, 1994). Tracks could be used on very soft ground(Murosky & Hassan, 1991) but then the trails should be as straight aspossible.

F. Environmentally friendly* The new harvesting system should be aimed to be environmentally friendly.

(1) Environmentally sound (friendly): a degree of disturbance to theecosystem due to the entry of some kind of human activity for the utiliza-tion of natural resources where the ecosystem functions can be recoverednaturally within a reasonable part of its lifecycle.(2) Environmentally sound forest management: implementation of forestryand silvicultural regimes to increase production of goods and services whilemaintaining the ecosystem integrity and environmental quality. Webb (1994)stated: "Forest management operations should encourage optimal/efficientuse of forests' multiple products/services, and to maintain critical ecologicalfunctions of forest and minmize adverse impacts on biological diversity, waterresources, soils, nontimber resources and unique/fragile ecosystems/lands-capes".(3) Environmentally friendly forest harvesting operation: removal of selectedtrees or other products with minimal impact on the biodiversity, sustaina-bility, and aesthetic values of the forest ecosystem. Webb (1994) stated:"Forest management operations should maintain/enhance long-term socialand economic well-being of forest workers and local communities".

* It should be energy efficient and have low degree of emissions. Recycablematerials, degradable oils, . etc should be used.

G. Cost efficiency* The harvesting system should be cost effective to make it possible to perform

the cuttings on an economical basis.

12

EXISTING MACHINE SYSTEMS

I. Harvesting

Feller-buncherFeller-buncher is a dual function machine which has gained considerable interestin the South. Different types of machines exist with shear heads, chain-bars orcircular sawheads. In the beginning, the feller heads were mounted onexcavators due to the size of old-growth forests but these tracked machineswere found to be less suitable for thinning operations. Wheeled machines withframe mounted fellers were replaced by felling heads mounted on short boomsto faciliate bunching. One popular machine for thinning applications is the three-wheeled shear feller-buncher Mor-Bell due to its small size and maneuverability.At fifth-row thinning operations, it can perform very well at low cost (Fig. 4). Lateron other machines have been introduced based on the same concept. Thedrawback with this method is that the machine has to travel to each tree andat selection cutting the travel-to-tree time as well as travel-to-dump will increaseconsiderably (equations given by Stokes et al., 1982 and Ashmore et al., 1983).The use of high flotation tires will decrease the foot print pressure but increasethe width of the machine and make it difficult to handle in a selection cutting andresulting in increased stem damage (Ostrofsky et al., 1986 and Whitney, 1991).The alternative would be to mount the feller head on a long boom and lift outthe whole trees. However, the whole tree is heavy (Fig. 3) and the brancheswould make it even more difficult to handle the felled tree between remainingstanding trees. It would be easier in this case to fell, delimb, and buck the treewith a harvester.

Tree processor and felling-delimbing-bucking machines (shortwood)A tree processor is a machine that can perform at least two operations but notfelling. Farm tractor mounted processors are quite common among privatelandowners in the Nordic countries as an intermediate between delimbing-bucking with the chainsaw and a harvester. In the USA, grapple processors havebeen tested in pine plantations (Greene et al., 1984) but the productivity mayhardly justify the third machine type between a feller-buncher and a skidder ora forwarder.

Many different solutions for felling-delimbing and bunching have come and gonewithout making any success. One example is to delimb and top the treestanding, before felling it (see Staaf & Wiksten, 1984). However, the long boomto make this operation possible, made the machine very difficult to handle.

13

70-

60-

| 50-

| 40-c0

a 3o-

CL 20 -

10-

0.03

/ . • •

0.09 0.19 0.33

Volime per tree, rrO

/

0.52

Hydro-Ax

Tri-Trac

Mor-Bell

Norcar

Borberg

Figure 4. Compiled productivity data for feller-bunchers and harvesters. Feller-bunchers with shear head: Mor-Bell (Stokes, Lanford & Sirios, 1982); Hydro-Ax 411 (Ashmore, Stokes & Lanford, 1983); GafnerTri-Trac (Rummer, 1993).One-grip harvesters: Norcar (Brinker & Tufts, 1990); general Swedish data(Brunberg, Norden & Tosterud, 1989).

Delimbing-bucking-bunching machines have found acceptance for work at thelandings but not for in-wood operations (whole-tree systems). In general, a thirdmachine between felling and extraction would increase cost with less improvedproduction. Thus, for the environmentally friendly operation, the number ofmachines should be kept as few as possible and an extra machine fordelimbing-bucking-bunching might not be a good approach.

Tree harvesterThe integration of the feller-buncher and a mobile processor into a singlemachine was achieved with the development of the harvester (Andersson, 1984).Since most operations at that time dealt with clearfelling, the large tree sizedemanded a powerful machine that could fell the trees with a tool in the boomand positioned them into the chassis-mounted processor (two-grip harvester).The two-grip harvesters became very popular in the Nordic countries during theeighties and soon most of the clearfelling work was mechanized (Freij &Tosterud, 1989). Development of measuring devices for tree diameter and lengthfaciliated computer-aided bucking.

14

* * Ii. i

Figure 5. A small harvester for shortwood production. It fells, delimbs and sortthe trees into sawlogs and pulpwood. The machine operates both on stripand access roads. One or two access roads could be used between thestrip roads where the forwarder collects the wood.

The two-grip harvester was, however, not very well suited for the thinningoperations. In the middle of the eighties, the first attempt with boom-mountedone-grip harvester started. With this machine, the whole operation (felling-efelimbing-bucking and bunching) was completed from the first grip. Today it hassurpassed the two*§rip harvester even in clearfelling operations, especially instands with small tM$». A number of different machines exists as well asseparate hawesting heads. The harvesting head sizes vary from 30 to 60 cmcutting dfarffeter with a mass of 300 to 1100 kg. Boom lengths can be 5.5 m forthe smallest harvester and up to 10 m for larger machines. In thinning operation,the one-grip harvester would operate from the strip road extending the boominto the stand to fell the trees. Delimbing should be done in front of the machineto add slash on the strip road and in that way armouring and reducing soildisturbande. At the end of eighties, the small 5-tonne harvester was introducedand this narrow machine could work also within the stand on access roads (Fig.5). Damage surveys showed that these small harvesters left almost unvisibletracks after passage and soil compaction from the wheels was minimal (Wilpert& Parbs, 1992; Jansson and Wästerlund, pers.comm). However, the acceptance

15

of the small harvesters has decreased due to its limited capability of cuttingdimensions. General performance data are shown in Figure 4. It should beemphasized that the harvester did the delimbing in the wood and no cleaning-upof the landing was necessary - which in the case of feller-bunchers might beput on the skidder and decreasing its productivity with about 15-25 % (Stokeset al., 1982). Thus, the performance is comparable to feller-buncher operations.

Soil and root damage levels are quite small but the large harvesters (> 10 tonne)may cause soil compaction even with the presence of debris (Jansson &Wästerlund, pers.comm.). The main limitations are: reduced ability to handlelarge trees, especially at distance, and the system is basically suited forshortwood.

II. Extraction

Helicopter loggingHelicopter logging is not a very new invention and the system is described byStewart (1978). The great advantage is the possibility to negotiate rough terrainand yarding distances can be long (up to 1.5 km) although the cycle time isdependent on flying distance (Hassan & Gupta, 1988). Production may be veryhigh (130 m3 per hour, Stewart, 1978) for large helicopters (Sikorsky 65 SkyCrane). The helicopter prices have gone down considerably, but still it is a ratherexpensive yarding metod. Sloan et al. (1994) described the new type ofhelicopter, K-MAX, with dual counter rotating main rotors to be an alternativelogging method for mountain forests giving a logging cost of about 33 USD m'3

at a hauling distance of 600 meter. The drawback is that the choking is donemanually. Tree harvesting can be done with a feller-buncher (Kirk & Kellogg,1990) but harvesters with delimbing devices are preferred in order to reducetransport weight. Sloan et al. (1994) calculated the lowest volume cut consideredfor the K-MAX to be 30-35 m3 per ha, which means the method would be bettersuited for a clearfelling operation with concentrated timber bunches rather thana selection operation. Noise and high fuel consumption make the helicoptersless environmentally friendly although ground disturbance for extraction may beminimal.

Balloon loggingBalloon logging is a more labour intensive method than helicopter logging. Theadvantages of balloon logging are long yarding distances, minimum soildisturbance, less damage to remaining timber stand, minimum crew hazard andelimination of spar trees or steel towers (Stewart, 1978). Balloon logging withthe pendulum-swing system is one improvement to get a more stable balloon,speed up the yarding cycle and decrease the required horsepower to run thesystem (Oisen et al., 1984). Balloon logging may be capable of harvestingisolated patches of windthrown and insect-infested timber (Oisen et al., 1984).

16

The system is clearly environmentally friendly but it is complex to set up andis weather dependent. Load per swing could be up to 5,000 kg. However, forthe small harvesting volumes in an EM stand, the costs for set-up can outweighthe benefits of balloon logging.

Cable yardingCable yarding is commonly used for steep slopes and many different set-upsexist (Lisland, 1975; Kochenderfer & Wendel, 1978; Conway, 1982; Aulerich,1990). It is a labour intensive method but when well done soil disturbance isleast especially when with high lead cable logging (Stewart, 1978). Theextraction method can fit both rough terrain conditions as well as steep slopes.However, the erection and logging in steep and bad terrain are hard work andexpensive, and the time for erecting and dismantling increases rapidly ith cablelength (Lisland, 1975), which means the forest road network should be denseand must be well planned with adequate landings. The extraction trails shouldbe straight within corridors (Kochenderfer & Wendel, 1978). The costs ofclearfelling may be about 15-19 USD m'3 (LeDoux & Baumgrass, 1990; andSloan, pers. comm., 1994) and rise rapidly with increased number of landingsper m3, decreased volume per tree, and yarding distance (Lisland, 1975), whichmeans the system is not very suitable for selective cuttings. Economically, itis a heavy and dangerous work. Although a feller-buncher may be used, riggingof the cables and choking remains manual.

yardingWith a grapple hanging on wires between the grapple yarder and a haulback,trees or stems awrbe picked up and hauled to roadside. The method may workin clearfelling operations with greater concentrations of timber, but has notshown economic feasability (Peterson, 1986). The only advantage wittvthismethod is the reduced traffic on the site and the possibility to transport stemsacross areas with low carrying capacity.

WinchingOn ground pulling of stems or logs as an intermediate system between cableyarding and skidding. Winching is a lowcost extraction method with lowefficiency, high pulling forces and often associated with high degree of damageto residual trees in a thinning operation.

SkiddingSkidding is the most commonly used method for timber extraction (Wästerlund,1994). The grapple skidder is more cost efficient than the cable skidder(Kluender & Stokes, 1992). Extraction distance influences the productivity very

.;** much (Fig. 6) and a skidding distance above 300 meter is not recommended.

17

JU '

25-

20-

ID-

S'

0-

\

\\

100

~ " Forwarder

Skidder

250 500 1000

One way distance in meter

2000

Figure 6. Compiled principal data for two extraction methods: Forwarding basedon data from Gullberg (1994) and skidding based on Roise & Hassan (1988).

Skidding may also be the only alternative when considering large trees or logswith more than 4-5 tonne (Hendrison, 1990). However, in a number of reports(Cromack et al., 1978), the extraction by skidding is considered to be one of themajor causes of soil disturbance due to the high skidding resistance forces(Hendrison, 1990). Jse of extra wide tires may reduce soil damage but alsodecrease the maneuverability of the machine on non-clearcut areas (Hassan& Gupta, 1988). Another possibility to reduce soil damage is to use a sulky(swing cart: see Southern Loggin1 Nov. 1994, p.45) to lift up the rear ends of thetrees. A drawback is that the machine carry small loads (4-5 m3) per turn, whichmeans more intensive ground traffic. Tree length is preferred but the long stemsinfluence road planning towards straight and wide skid trails similarly. Shortwoodincreases the traffic and decreases the productivity. Clam-bunk skidders cantake large loads and are efficient on long distances but have in principle thesame drawbacks as ordinary skidders.

ForwardingForwarding is mainly used in Canada and the Nordic countries. The mainadvantage is that the machines carry the load, which means less skiddingresistance, jess soil particles on the timber, and less soil damage. However,its performance will depend on the machine design and the tire sizes andarrangement. The forwarder is often equipped with bogies both front and rear

18

to reduce ground pressures, increase traction, and improve the comfort. On theother hand, bogies cause side skidding forces when operating on cross gradesand curves. Studies have shown less soil damage with forwarding comparedto skidding {Wronski 1984; Lanford et al., 1991; Thompson, 1991). Forwardingworks best with shortwood systems and due to loading and unloading time, itcan only compete with skidders on long extraction distances (Fig. 6). Anotherbenefit is that the area required for roads and landings for temporary storageof the timber is much smaller than for skidding (Kellogg & Bettinger, 1994).

Horses and oxenExtraction with the help of horses and oxen and proper equipment (trailer withloader or sulkies) have gained some new interest. The benefits are the lowinvestments, adaptability to stand conditions and with low number of passes littlesoil damage. However, the method is labour intensive and productivity is low(Staaf & Wiksten, 1984).

Air-cushion vehiclesAir-cushion vehicles have been considered for log transportation but due to theiralmost absent contact with ground, the sideslope negotiation is also absent. Soildamage can be reduced to near zero but instead dust problems may arise.

ChutesTransportation of logs in chutes or tubes downhill has been tested in theAppalachian mountains in the beginning of the century. The V-shaped log slidescan be up to four km long along the valleys in the mountains (Weal, 1993). Theset up of the system is labour intensive and to be efficient the method needsfcjpjih a concentration of timber and steep slopes. Friction can be dimished withhelp of water transportation in the tubes or low friction material in the chutes(Warkotsch, pers. comm). An environmentally friendly extraction method whenproperly done but the method is depenttent on having rather steep slopes andis potentially unsafety.

RailroadRailroads were the only way to transport the logs out from the foroatto the millin the old time (Weals, 1993). With old-growth forests, the sizes of the logsdemanded heavy equipment. Railroad haujjrjö was best suited to these highvolumes, high tonnage, and hauls exceeding 500-600 km (Conway, 1982). Withpresent density of forest roads, the costs for building of railroads can never bejustified.

III. Combined Methods

Feller-forwarderOne way to reduce the traffic on the site is the use of multi-purpose machinery.

19

One concept is the machine that can fell the trees and transport them to thelanding. The multi-function aspect:~> accomplished with minor complexity thana feller-buncher (cf. Conway, 1982). It offers a high man/day productivity anda tidy operation (Kurelek, 1984) but these statements may be questionned.Koehring feller-forwarder is the most known type. The drawback of the methodis when high volumes are to be cut on long forwarding distances which meansa low utilization of the felling head. In principle, the method can be very usefulfor selection operations with low cut volumes, especially at places with shortforwarding distances. For selection cutting with winding roads, the stem lengthscan be a problem. Preferably the slash are kept on site, partially to reinforce thestrip road, which means the machine is to be equipped with a delimber head.

Feller-skidderThe feller-skidder is, in principle, the same concept as above (Staaf & Wiksten,1984, p.91). Usually it is equipped with a clambank for the trees and forimproving machine stability. This machine type may have a further disadvantagein the selection cutting by dragging the trees and thus damaging the residualtrees more than the feller-forwarder.

Harvester-forwarderIn the beginning of the nineties the Nordic company Valmet introduced aharvester-forwarder, aiming to reduce the number of needed machines and forsmall operations. Time studies on the machine showed, however, that at normalforwarding distances, the harvesting head was under-utilized and not reallybeneficial. The question of the suitability of this machine for selection cuttingsis not yet proven. The same conclusions concerning the feller-forwarder above,are valid for this machine type too. Experiments with this machine type is on-going in the Nordic countries.

In-woods chippingChipping at roadside has been of interest since the seventies (Plummer, 1981).Early developments were associated with production of fuel-wood. Manysystems have been tried and the main drawback has been the problems for pulpmills to accept chips with bark contamination. Lately, mobile delimber-debarker-chipping machines have been developed to produce chips of high quality forpulp mills. Cost analysis of such systems, considering all costs to ready chipsat the mill, show that chipping at landing can compete successfully withroundwood systems especially with small diameter trees (Favreau, 1992).However, frequent moves will increase the costs and chipping at landing cantherefore be of less interest for selection cutting. A benefit with whole treechipping is a higher degree of utilization of the wood fiber resources (Herrick,1982).

Studies on off-road chippers carried on forwarders have shown a reduced

20

productivity (but not necessarily higher costs) compared to chipping at roadsideand with a shuttle, the production may increase but not necessarily reduce thecosts (Richardson, 1986). With frequent relocation, a mobile off-road chipper ismore economic than a landing type, because of low set-up time (Richardson,1986). The mobile chipper can also be used to clean-up the area and reducefuel for forest fires. However, whole tree utilization may be restricted in someareas for EM. Another drawback with off-road chippers is their weight. Withouta slash mat an extensive rutting can occur (Richardson, 1986) and means toreduce weight of the machine and to increase the flotation is necessary. InSweden a delimber-debarker-chipper with a chip hopper has been developedto be mounted on a farm tractor (see p. 198 in Staaf & Wiksten, 1984). It isdesigned forsmall diameter trees and to work in first thinnings. Chip quality hasbeen found to be good but the economy is not always acceptable.

The main advantage with inwood chipping is a better recovery of wood fibers.However, transport costs for wood chips may be high since the material has lowdensity. Some kind of compaction of the material is necessary to improvetransport economy (Hassan, 1977). Still, the present system need a pre-fellingand bunching of material. Direct feeding with a felling head has been tested butappeared to be time-consuming with low utlization of the complicated andexpensive machine. Fire hazard is reduced through the removal of combustiblematerial from the wood (Richardson,1986).

EVALUATION OF EXISTING MACHINE SYSTEMS

An attempt to evaluate harvesting and transporting machines is summarized inTable 1. The evaluation is based on the assumed suitability for application inecology management according to the requirements stated in the section above,and accounting the best machines/methods in each category that exist today.The scores are subjective and each category has the same weight. In reality,the cost efficiency should havQj&auble weight, which in turn would favour forinstance the feller-buncher afRHkidding system.

Our evaluation shows that no machine or method recieved maximum scoresfor all aspects. However, the addition of all scores (column 9 in Table 1) couldmake it easier to get an overview of the machine performances. The suitabilityof the listed machines and methods for an EM operation can be classified as:

scores 18-21 recommendedscores 14-18 acceptablescores < 14 unacceptable

21

Table 1 . Summary of the evaluation of the different methods to extract andharvest the timber in an ecology management silviculture regime. Legends:3 = good; 2 = average; 1 = poor

Harvesting

Fell-bunch

Processor

Harvester

Extraction

Helicopter

Balloon

Cable yard.

Grapple y.

Winching

Skidding

Forwarding

Animals

Air-cushion

Chutes

Railroad

Combined

Feller-forw

Feller-skid

Harv-forw.

Chipping

A

3

2

3

2

1

1

1

2

3

3

2

2

1

1

2

2

3

3

B

2

3

3

3

3

3

3

3

2

3

2

1

2

1

3

2

2

2

C

1

1

3

2

2

3

1

2

2

3

3

2

3

1

2

2

3

2

D

3

2

1

3

3

3

3

3

3

2

2

2

2

3

2

3

2

2

E

1

2

3

3

3

3

3

1

1

3

2

3

3

1

2

1

3

2

F

2

2

3

1

3

3

2

2

2

3

3

1

3

3

2

2

3

1

G

3

1

2

1

1

1

2

2

3

2

1

1

1

1

1

1

2

2

Total scores

15

13

18

15

16

17

15

15

16

19

15

12

15

11

14

13

18

14

Table footnotes:A: System requirementsB: Road and terrain requirementsC: Space/clearance requirements

D: Tree handling requirementsE: Acceptable degree of damageF: Environmentally friendlyG: Cost efficiency

22

The evaluation shows that some of our present methoos, such as shortwoodwith the use of a harvester and a forwarder, could be recommended and thatall recommended machines and methods are ground-based. Harvesters arebetter than feller-bunchers mainly due to the long reach of their boom. Theboom-mounted head, together with the shortwood method will reduce the trafficin the stand and provide slash residues on the roads. Although the feller-bunchercan have a low ground pressure, the number of passes to approach the treeswill increase the load on the soil (Wronski & Humphreys, 1994). The drawbackwith the harvesters are the lack of capability to handle big trees, which partlydepends on the machine stability and strength of boom. The exception fromalready commonly used machines in the list, is the harvester-forwarder. Thismachine type got high scores for the single machine operation, which meansalso easy to move and suitability for low volume operations.

The most used types of machines and methods today are found acceptable.Cable yarding is still the main alternative for steep terrain operations.

The conclusion from our evaluation is that we do have acceptable systems butimprovements seem necessary for future successful operations. It is obviousthat future development should continue with ground-based machinery.

CONCEPTUAL DESIGNS FOR THE FUTURE

As shown by Stokes et al. (1992), a selection cutting operation would decreasethe productivity of an ordinary method and put a demand on improving thetechnique. The system should be ground-based and work without permanentroads. Light and multi-purpose machines would be preferable, although it maybe difficult to handle big trees with sueh machines. Further improved tires forlow ground pressure and good traction, and application of variable tire pressureinflation (VTP/CTI) - as proposed by Zealley (1990) - could be one of the waysto decrease soil disturbance by heavy machinery. Further, the machine shouldhave a boom or crane for multi-purpose tasks: felling, processing, loading, piling,spacing operations, site preparation and planting by simply attaching the righttool to the boom. For selection cuttings a one-grip harvester head would bepreferred because of the small space requirements. Delimbing of trees couldthen be done in the stand and preferably in front of the machine and therebyspreading out the slash in the stand. Piles of logging residues can otherwise bea problem (McKenzie & Garret, 1994). Preferably the harvesting head shouldb%j0to to handle multiple stems to increase productivity when working withsmalt trees (Brunberg et al., 1989).

The base machine should have hydrostatic transmission drive which mightincrease its cost. However, the machine versatility should increase giving more

23

freedom for alternative designs. A traction/slip control could be of advantage(Mohr & Eriksson, 1993).

The wheels could be assembled on hydraulic controlled pendulum arms (Fig.7), thus eliminating the traditional axles and allowing operation on uneventerrain. This type of machine could have articulated steering without the useof pivoting joint, which will increase machine stability.

Skogsjwi487SochXL

Z780 (med 700»34j

Figure 7. A conceptual machine for a one-grip harvester. Boom length10 m and lifting capacity of 160 kN. Machine mass 12 tonne. The machinehas hydrostatic transmission with independent wheel motors and the wheelsare placed on hydraulic controlled pendulum arms for operating on uneventerrain.

With maximum 20 % trafficked area, the harvesting machine should have 9 -10 m boom to reach out between the trails. The capability to lift large treeswould be reduced as the reach distance increased. Theoretical calculations onthe harvester shown in figure 7, show that the machine with a weight of 120 kNis unstable at loads above 25 kN for a boom reach of 10 m when lifting at thefront of the machine (Fig.8). At 90 degrees angle the stability is less and max9.1 kN can be lifted. From those values the weight of the felling head (10-11kN) should be subtracted. A comparison with the tree weights in Figure 3 showsthat only small trees can be handled with this long boom reach (h reality thegross lifting capacity of 160 kN on that machine will be limiting when working

24

O

X(O

200

160

120

80Machine weight,

kN

Boom length, m

Figure 8. Theoretical calculation of the maximum lifting capacity when lifting inthe front direction with a boom of different length without turning over. Theprincipal model for calculations is the machine presented in figure 7 and themass of the boom is assumed to be 1500 kg.

straight forward). Tractor excavators have supporting arms for increased stabilityand similar ones could also be used on forestry machines, e.g. arms that areautomatic extended to increase the machine stability with a certain load on theboom. Calculations show that automatic arms extending only 1 m would increasethe maximum load for stability in the front direction to 46.6 kN and at 90 degreesto 27.2 kN. Thus, a simple device will have a great effect.

Boom construction and strength are another area for development. The presentbooms are rigid to allow easy handling but actually an elastic one may be ableto handle larger weights. Computer-aided boom control has been developed(Löfgren, 1989) without common acceptance. However, a computer-controlledelastic boom would be very difficult to develop. ^

•mmMachinery for extraction has operated on the same princips since inception inthe early sixties. Machine extraction productivity has not changed very muchduring the last decade. One way to improve both comfort and travel speedscould be to supply these machines with semiactive/active suspension and chockabsorbars.The technology is available but will demand R & D for forestryapplications. At long extraction distances, the "Rattler" technique could be used.

25

The Rattler is a wheeled toy with a number of powered units connected to eachother with pivoting finks.

If the base machine is equipped with hydrostatic transmission, additional loadingunits (trailers) could be attached with pivoting steering connection, thus creatingan off-road train.

As mentioned earlier, the harvester-forwarder concept can be of value forselection cuttings. The main drawback is the low ulitization of the harvesterhead. One idea that could be worthwhile to test, is to combine that machine witha separate chipper/hopper. The harvester-forwarder fells, delimbs and bucksonly the sawlogs, thus working with valuable products that benefits fromseparate handling. The low value pulpwood is piled along the strip road whichin turn will improve the capacity of the inwood chipper. If the slash is to remainon site, the chipper can be equipped with a delimber and debarker to produceclean pulpwood chips.

The machines should of course have biodegradable hydraulic oils. It iscommonly used in new machines for the Swedish market. Some problemsexisted but with improvements, the new oils provided lower temperatures in thehydraulic system.

Finally, we have taken the man off the ground, so why not continue and liberateman from the machine. Robots are becoming more capable to make outdoororientation and within 10 years, some prototypes may be working in forestry.Meanwhile, some components should be utlized on the present machines (e.g.boom control). One conceptual machine is presented in the table of content(Gellerstedt, 1994). The base machine for the robot can be designed aswheeled, tracked or walking beam. A wheeled version could very well be basedon the Quadractor concept. The Quadractor was developed during the seventiesby an airplane designer and has a very intelligent wheel suspension system,among other interesting concepts (Sarna, 1978; Stevens & Smith, 1978). Fortimber transport of timber, the designer proposed a grapple under the chassis,which is genious since the more load it takes, the lower the center of gravity itgets.

Some few walking machines exist and one type has been tried out for forestryapplications (Stuart et al., 1992). In many forestry operations, a walking machinecan fit very well, in harvesting, spacing and planting. A walking machine usesconsiderably less energy for movements than a wheeled machine, since it lacksthe rolling resistance. It can operate on uneven terrain and can move sideways.The latter aspect makes that machine very easy to position. Walking machinesmay be too expensive and fragile for forestry work but they provide basicplatforms for future forestry robots.

26

CONCLUSIONS

A general trend in the world is to cut down on machine R&D for forestry

operations, implying that new machines are not needed. However, the new

silvicultural trends towards ecological management of the forest will demand

some other machine concepts than the present ones. Some ideas are presented

here but we need to know how to handle large trees in selection cuttings in a

smart way. Robotic technique will come but it needs high R & D input to get self-

controlling robots well working in a forestry operation.

Another aspect is where to handle and sort the trees: in the forest, at the

landing, or at final destination. If the goal is transport of valuable products, then

proper handling should be done in the forest with good technique to avoid

lowering the values.

Acknowledgement

Appreciation is extended to the Nicholson Trust for sponsoring Iwan Wästerlund,

Swedish University of Agricultural Sciences, visit to North Carolina State

University.

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NEN FÖR SKOGSTEKNIK (Pris: 50 kr + moms, om inte annat anges):

LIST OF "UPPSATSER OCH RESULTAT" PUBLISHED BY THE DEPARTMENT OF OPERATIONALEFFICIENCY FROM 1994 ONWARDS (Price: SEK 50 unless otherwise stated):

1994

Nr 264. Uppgård, R. Tidsstudier av mobila sågverk - Laimet 120 - och Wood-Mizer LT 40 HD.(Under utgivning).

Nr 265. Nordfiell, T. Studier av framkomlighet och lastbärande förmåga för små terrängfordon. Studiesof mobility and load capacity of small terrain vehicles.ISRN SLU-ST-UPPRLT-265-SE

Nr 266. Nordfiell, T. Framkomlighet i snö med små terrängfordon och häst. Mobility in snow withsmall terrain vehicles and horses.ISRN SLU-ST-UPPRLT-266-SE

Nr 267. Nordfiell, T. Jämförande tidsstudie av gallring med miniskotare. Metod, tidsåtgång, arbets-belastning och ekonomi. Comparative time study of thinning with mini-forwarder. Method,production, work load and economy.ISRN SLU-ST-UPPRLT-267-SE

Nr 268. Johansson, J. Översikt av erfarenheter av anläggningsmaskiner som basmaskiner i skogsbruket.Eanh-moving equipment as base machines in forest work - an overview.ISRN SLU-ST-UPPRLT-268-SE

Nr 269. Liden. E. MASKINENKÄT -93 - maskiner, volymer och ägandeformer i storskogsbruket iSverige utfall 85/86, 92/93 samt prognos för 97/98. MACHINE INQUIRY -93 - harvestingsystems, ownership and volumes in Swedish forest enterprises outcome 85/86 and 92/93 andprediction for 97/98.ISRN SLU-ST-UPPRLT-269-SE

Nr 270. Bertilsson, L. & Synwoldt, U. Småskalig torvproduktion. Del 1. Driftsuppföljning och maskin-studier. Small-scale peat production. Part 1. Operational studies and machine performance.ISRN SLU-ST-UPPRLT-270-SE

Nr 271. Synwoldt, U. Småskaligt torvproduktion. Del 2. Beräkning av produktionsresultat för olikamaskinsystem. Small-scale peat production. Part 2. Calculated production for different machinesystems.ISRN SLU-ST-UPPRLT-271--SE

Nr 272. Johansson. J. Lantbrukstraktor som basmaskin - Ford 276 Versatile med engreppsskördar-aggregat samt griplastare och vagn. Farm tractor as base machine - Ford 276 Versatile with asingle-grip hatvester head and grapple loader and wagon.ISRN SLU-ST-UPPRLT-272-SE

1995

Nr 273. Liden, E. Inquiries into Harvesting Systems, Quantities, and Machine Ownership in SwedishIndustrial Forestry - status 1985/86 and 1992/93 and prediction for 1997/98.ISRN SLU-ST-UPPRLT--273--SE

Nr 274. Liden, E. Attrition in Swedish Forestry Work 1986-1990 - Extent and Causes.ISRN SLU-ST-UPPRLT-274-SE

Nr 275. Miring, B. Utvärdering av skogsbränslesystem med träddelsterminaler - Projektutvärdering ochmetodutveckling. Evaluation of forest fuel systems with tree-section terminals - Projectevaluation and method developmentISRN SLU-ST-UPPRLT-275-SE

För den som är intresserad att ta del av tidigare utgivna publikationer i institutionensför skogsteknik serier "Stenciler (1974-1984) respektive "Uppsatser och Resultat"(1984-) kan en publikationsförteckning rekvireras med hjälp av nedanståendetalong.

For those interested in studying previous publications in the series "Stenciler" (1974-1984) and "Uppsatser och Resultat" (1984- )from the Department of OperationalEfficiency, there is a list of publications available, which can be ordered by using theform below.

Härmed rekvireras ett exemplar avinstitutionens publikationsförteckning.

Please, send me a copy of the list of publicationsfrom the Dept. of Operational Efficiency.

Namn:Name:Adress:Address:

Sänds till: Margareta NyströmMail to: Sveriges lantbruksuniversitet

Inst för skogsteknikS-776 98 GARPENBERGSweden

Distribution från Ansvarig utgivareA vailable from Responsible for the publication

Sveriges lantbruksuniversitetInst. för skogsteknikS-776 98 GARPENBERG Pris: 50 krTel:0225-26000 Price: 50 SEK