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Slovak forestry (a complex of activities leading to conservation, protection, improvement and rational use of forests) is an important state sector from the point of view of coverage (40.6% of total surface area), in terms of the significance of functions drawing on forest potential (for example, environmental, landscaping, recreational, sanitation, water management, cultural and educational, and raw material source), and from the point of view of historical tradition. It is in the country's interests to permanently improve and optimize the use of forest potential.

Up to 1989, the year of important political and economic changes in Slovakia, the main system in use was small area clear cutting. However, considerable changes regarding the principles of forestry policy and forest management systems were ushered in as a result of changes on the domestic front, and of important international events such as the 1992 United Conference on Environment and Development in Rio de Janeiro, which included basic principles for sustainable forest management, and the 1995 Helsinki Ministerial Conference, which passed a resolution on the protection of European forests. In line with international public opinion, these changes offered favourable conditions for a return to the principles of the shelterwood management system that had been applied throughout Slovakia's forests in the 1970s and 1980s. In the period 1984–87, the shelterwood system covered 16% of total regenerated forest area, and by 1993–94 this had risen to 38% through the provision of forest management plans, and the selection system accounted for 2% (Report on Forestry in the Slovak Republic 1997).

In terms of the low contribution of forestry to national income (2%), it should be noted that Slovak forestry is mainly concerned with sustainable forest development and striking a balance between production and the ecological impact of human activities in forests. Activities aimed at wood production in forests must be subordinated to this principle. It is necessary to determine a limit below which the consequences of using forest techniques do not endanger forest survival. One this has been ensured, the next step is ensure quality control of the logging machines used in terms of potential damage to stands and soil.

Prospects for implementing environmentally sound forest techniques

Inappropriate use of forest techniques and the non-adaptability of the techniques themselves have a negative effect on forest areas (see Table 1).

Stand land and its components are being damaged and the air polluted. In turn soil is being eroded by water, fertility is being reduced and the quality of ground water and streams is deteriorating. The aim must be to create and use technical means, technological processes, legislation, data and assessment mechanisms that will help limit the negative effects of forest techniques to a minimum.

Table 1: Negative effects of forest techniques

MeansSourceManifestationConsequenceImpacts on standRemedial measuresLevel of damageInvestigatorNote
     PrematureMature  ForestryNational Economy 
Energy SourceNoiseDisturbance of recreational function 0xBafflers10x 
Fumes - exhaustDamage to flora xxCatalyzers20x 
Oil product waste:
• motor/working oils
• lubricants
Deterioration of soil and water xxBio-oils3xx 
Fuels  xxNatural petrol, bio-diesel3xx 
Travelling and working parts Soil pressingReduction of soil fertilityxxLow pressure tyres30x 
 Damage to standDepreciation of productive qualityxxWork in stand only with rope, tractor in line3x0Light direction sheaves
 Damage to undergrowthInhibition of stand regeneration0x-3x0Change of remuneration
 Damage to rootsReduction of growthxx-3xx 
 Soil disturbanceWhole-area erosion, soil wash-away, water and basin pollutionxx-


x0Better quality of access to stand
Energy sourceNoise  0xAs for tractor10x 
Fumes - exhaust  xx-10x 
Oil product waste:
• motor/working oils
• lubricants
Fuels  xx-2xx 
Travelling and working parts Damage to standDepreciation of productive qualityxxRemote control of cable by tripper2xx 
 Damage to undergrowthInhibition of stand regenerationxx-
Motion Damage to standDepreciation of productive qualityxx-1x0 
 Damage to undergrowthInhibition of stand regenerationxx-1x0 
 Damage to rootsReduction of growthxx-1x0 
 Soil disturbanceWhole-area erosion, soil wash-away, water and basin pollutionxx-



Notes: Damage - 1 = light;
2 = medium;
3 = heavy

Impacts on stand - 0 = no;
x = yes

Investigator - 0 = no;
x = yes.

Power saw timber felling

Power saws for timber felling represent the most negative form of forest techniques, through environmental contamination from lubrication oil. Currently, Slovakia is substituting mineral-based lubricants with rapeseed oil, which is highly bio-degradable by soil micro-organisms. After an initial phase of rapeseed oil use in the Tatra National Park, its use was extended to other protected areas and commercial forests. However, the level of use compared to traditional lubricants is still insufficient.

Recently, the Forestry Faculty of the Technical University in Zvolen has been testing a number of other mineral-based oils such as Upil R (produced by Petrochema Dubová, Slovakia), OA M6A (Ostramo Ostrava, Czech Republic), and a number vegetable oils such as Primol EkoP (Setuza š.p. Lovosice, Czech Republic), Biosegarol E 100 (ÖMV, Austria), Ekopil (Petrochema Dubová, Slovakia), Biopil I (PeWaS s.r.o., Slovakia), Ekorezol (Chemko Stráske š.p., Slovakia) and DAVOZ (Ekol s.r.o., Slovakia).

It is expected that broader use will be made of power saws using ecological lubricants, after the introduction of a subsidy system allowing lower prices than for mineral-based lubricants.

Tractor skidders, harvesters and forwarders in timber felling

The greatest damage to forest areas occurs during tractor skidding operations, depending on the type of felling involved (whole stems, logs, trees), access to forest stands (density of skidding roads and lines) and equipment components (types of equipment, motors, tyres).

The most favourable skidding method is the machine assortment method, in which harvesters and forwarders move only along a determined line, with a layer of settled felling residues. However, this method can be applied for only 120,000 m3 of timber (2.4% of the 5 million m3 permitted annually). Appropriate machines for this technology have been developed in Závody (heavy machinery plant), by the Lesné Stroje state enterprise (forest machines), in Trstená (LKT harvester with FARMI cutting head for thinnings and principal felling) and by the Zvolen Forest Research Institute (Dunaj 6T forwarder for thinnings).

In the field of tractor, harvester and fowarder use in Slovakia, there is a trend towards substitution of conventional mineral fuels, pressure systems and lubricants by ecological alternatives. Despite the use of mineral-based systems in machines at present, tests are under way of the special LKT 90 forest tractor using synthetic hydraulic lubricants. In 1999, the Forest Research Institute plans testing the Slovak-produced compound bio-oil BIOMON 97 in universal and special wheeled Zetor and LKT tractors. In order to reduce damage and pressure on soil, mainly on flysch soils in mountainous terrain, there has been a trend towards application of wide low-pressure tyres. LKT tractor producers supply the machines with conventional as well as with wide low-pressure TRELEBORG tyres. The Forest Research Institute in Zvolen plans to produce a prototype ORAVA T6 forwarder this year on the basis of the universal Zetor 8250 tractor, with wide 400/60–15.5 low-pressure tyres from Sweden. Recently, the Forestry Faculty in Zolen has developed the SPN-40 tracked traction unit, with manoeuvrability on slopes up to 50%. The data for unit pressures of forest tractors in track in Slovakia are presented in Table 2.

Sound silvicultural subdivision of forest land and use of a combination of skidding winch and forest tractor provide an almost certain possibility of reducing the negative effects of techniques on the forest environment.

Table 2: Specific tyre pressure of forest tractors in track

Type of tractorSpecific pressure in track
UKT with standard equipment (winch, front stacking blade, protective vat)160
UKT-Horal with forestry equipment, wider wheel spacing, wider tyres and different distribution of axle load compared to the UKT with standard equipment100
LKT 80 with standard equipment200
LKT 81 with standard equipment200
LKT 81 - logging machine on special wheeled chassis220
LKT 81 with low-pressure, wide-profile tyres - logging machine on special chassis with half-track  70
LKT 81 with tyre 23.1–26100
Special track chassis of RATRAC type35–50

The Forest Faculty in Zvolen has recently developed the small tracked MPN 3.7kW pulling unit, which is similar to the Husqvarna iron Horse skidding unit. The private KOMI (cables and tows) firm in Slovakia has developed the Lesan-50 wheeled and tracked skidding unit, involving a number of modifications in use of tractor and cable timber skidding operations.

Timber skidding by cable systems

In sloped terrain over 40%, wet land and the flysch zone, there is a tendency to use remote controlled cable systems to extract wood from stands. It is important to increase the level of use from the current 2.7% of total timber volume to around 12%. (In Austria, where the terrain is very similar to that of Slovakia, cable skidding accounts for more than 30%). A general lack of interest in cable use in Slovakia has been compounded by high purchasing and operating costs, and more demanding technological preparation. Special wheeled forest tractors are used on slopes up to 50% alongside cables in mountainous terrain. A special programme has been prepared for regeneration of cable skidding, covering the entire field of Technological preparation of stands, and the construction and operation of cable facilities. An important component of this programme is the adoption of a new system for calculating cable skidding costs and the introduction of additional mechanisms to reduce the high operational costs of cables compared to alternative skidding methods.

Transportation of timber by truck

Ecological measures taken since the beginning of 1998 include the gradual replacement of mineral-based oil by mixtures of BIOMON 97 bio-oil in LIAZ and TATRA haulage trucks in cooperation with producers and the Forest Research Institute in Zvolen. Further, the mineral-based OHM 46 lubricant in locally-produced ESSEL hydraulic grapple loaders has been substituted by the ecological EKOHYDROL hydraulic lubricant produced by the Chemko Strážske š.p. state company.

Two necessary conditions for the success of this trend are the availability of price compensation for mixed bio-oil and ecological hydraulic oil as against mineral-based lubricants and the mineral-based OHM 46 lubricant through a subsidy from the Ministry of Agriculture, and approval by producers of LIAZ and TATRA trucks on the basis of laboratory and operational tests carried out by the Forest Research Institute in Zvolen.

A major issue concerning the transportation of timber by trucks in Slovakia is to overcome the problem of overloading long timber hauling sets by developing new trailers with higher carrying capacity, and equipping log and whole stem hauling sets with devices to ascertain, signal and register axle loads (to combat overloading). The search for a solution started in 1994 at the Forest Research Institute's research station in Oravský Podzámok and is continuing. The aim is to reduce damage to forest roads caused by overloading of long timber hauling equipment.

Transportation of timber by helicopter

This form of transportation is taken into consideration where extraordinary circumstances do not permit use of other methods or when alternative transportation would be more expensive.


One of the most frequent questions about forest management in Slovakia concerns the ecological limits to use of forest techniques. However, due to insufficient knowledge about the negative effects of techniques on forest areas, it is impossible to determine fixed limits for their use. There is a need to set up an international project to study the problem from the point of view of the impact of various techniques on forests, and to identify recovery measures aimed at repairing damage, control mechanisms and financial resources for recovery in a multi-disciplinary approach.

Currently, the Ministry of Agriculture is preparing measures aimed at reducing the influence of the negative effects of logging techniques on forests, as a temporary step until overall regulations have been established for forest operations in this field. Such regulations depend on the results of the research referred to above.

Legislation and financial support for the ‘ecologization’ of forest management

Legislative support for ‘ecologization’ should lead to a ban on harmful lubrication and hydraulic systems in special regions (protected zones and regions, drinking water sources and water basins, and national parks), as is already the case in Austria and the Czech Republic, and to a ban on the use of lubricants for power chain saws that contain additives, including halogens and compounds of cadmium, mercury and arsenic. A similar ban is included in Regulation 647 (September 1990) of the Federal Ministry for Economic Affairs, referring to certain additives and the use of oil for chain saws from Austria. The Forest Act under preparation should contain these bans.

Finance for the ‘ecologization’ of forest management comes from the state. The basic financing institution is, and will continue to be under new legislation, the State Fund for Forest Improvement, which had SKK 593 million available in 1997.

In January 1998, the Ministry of Agriculture introduced a subsidy policy under Decree No 116/1998-100, through which the ministry can provide subsidies to users of mixed bio-oil in machines and to producers of bio-oil using rape seed methyl ester technology.

According to the Forest Research Institute in Zvolen, the ‘ecologization’ of Slovakian forest technology will require SKK 116.7 million in subsidies.

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