by
Anton Trzesniowski
Institute of Forest Engineering
1. INTRODUCTION
Austria is a typical county of small forest enterprises. The overall forest area of 3 876 999 ha is part of 214 464 holdings. Per capita distribution of the forest area is 0.5 ha/inhabitant.
Table 1
Forest economy in Austria
Land area: Population figure: Population density: |
8 385 266 ha 7 623 000 91/km² |
Forest area: Forest area per inhabitant |
3 876 999 ha (46%) 0.5 ha |
|
Forest area: Hectares Percent Number of owners |
Small holdings (up to 200 ha) 2 058 180 ha 53% 213 131 |
Forest estates (more than 200 ha) 1 237 759 ha 32% 1 332 |
Federal forest 581 060 ha 15% 1 | Total 3 876 999 ha 100% 214 464 |
Tree species: |
Coniferous 77.8% spruce 62.2% fir 2.7% larch 5.0% pine 6.4% others 1.5% |
Deciduous 20.3% beech 9.8% oak 1.7% other hardwood 5.2% deciduous softwood 3.5% |
Shrubwood 1.9% |
Total 100% |
Growing stock and increment (m3) Growing stock m3/ha Increment per year Increment/ha |
Small holdings 522 081 000 284 19 379 000 9.6 |
Forest estates 307 032 000 300 8 801 000 8.0 |
Federal forest 137 999 000 314 3 236 000 6.8 |
Total 967 114 000 293 31 416 000 8.7 |
Cuts m3 |
9 738 000 |
7 123 000 |
2 985 000 |
19 846 000 |
Categories according to forest area owned are listed as follows:
Table 2
Categories and holdings according to forest area
Categories according to forest area owned |
Holdings number percent |
Forest area hectares percent | ||
below 5 hectares |
139 566 |
65.0 |
270 350 |
8.4 |
between 5 and 20 hectares |
57 242 |
26.7 |
547 456 |
16.9 |
between 20 and 50 hectares |
11 946 |
5.6 |
356 419 |
11.0 |
between 50 and 200 hectares |
4 377 |
2.1 |
401 893 |
12.4 |
200 hectares and more |
1 333 |
0.6 |
1 660 717 |
51.3 |
Total |
214 464 |
100.0 |
3 236 834 |
100.0 |
The average forest area per holding is 15 ha. For owners below 5 ha, however, this figure is reduced to 1.9 ha per enterprise. The average area owned is 9.5 ha for the category between 5 and 20 ha, 30 ha for the category between 20 and 50 ha, and 92 ha for the category between 50 and 200 ha. For the category of largest owners the average forest area is 1 246 ha per enterprise.
This patchwork of ownership categories naturally affects any kind of mechanical operation. Recent technologies and flexible thinking have however helped to adjust to local requirements, preserve nature and protect the environment, at the same time observing the principles of sustained yield. In many cases, reluctance to employ machinery is caused by the weak financial situation of forest owners, which is further aggravated by low timber prices, high incidental expenses and heavy competition. Yet, timber harvesting is a matter of survival for many small owners, particularly for mountain farmers.
2. OPENING UP OF AUSTRIAN FORESTS
Opening up of forests is the most crucial investment needed to make timber extraction cheaper. Compared to traditional planning and staking-out, the zero-line method according to Hafner is directly applied on the landscape and is 8 to 10 times faster and cheaper. General opening-up of Austria's forests is based on a main forest road network accessible by truck of 135 700 km length and strip roads of 140 000 km length.
Main roads include 38 700 km of public roads with the dual function of transport and opening up and 97 000 km are forest roads constructed and maintained by forest owners. Based on the assumption that one ha of forest is required to build 1 km of forest road, forest roads owned and maintained by forest owners make up 2.5 percent of the total forest area. Public forest roads cover approximately 1 percent, and secondary strip roads account for 3.6 percent of the total forest area.
Since 1 km of main forest road costs A.S. 350 000, the overall investment of Austrian forest economy into general opening up of forests amounts to A.S. 34 billion.
If detailed opening up by strip roads starts early enough, the loss of area can be compensated by regeneration along the road clearing. Studies have shown that secondary strip roads covering up to 20 percent of the forest area do not affect growth increment.
2.1 Forest road width
Austrian forest roads have been heavily criticized for their width. The Forest Report of 1992 shows that 75 percent of forest roads in small ownerships have a width of 2 to 3 m and 25 percent of 3 to 5 m. In forest enterprises 43 percent of forest roads are 3 to 5 m wide and within the Austrian Federal Forest Estate 50 percent are between 3 and 5 m. In contrast to public roads, forest roads vary in width since they have to be adjusted to the terrain. Their foremost functions are however operational, i.e.: working site, loading and storing site and way of transport.
The highest cost share in timber harvesting is attributed to logging which may also cause considerable damage to soil, remaining stand and timber. It should therefore be given highest priority in the wide area of forest engineering.
Table 3
Timber logging (Forest Report 1992)
|
Type of logging |
mio m3 |
% |
Ground skidding: manual animal mechanical |
1.690 0.149 7.665 |
13.88 1.22 62.96 |
Cable crane Chutes, sledges Forwarder Others |
1.769 0.087 0.542 0.274 |
14.53 0.69 4.46 2.26 |
TOTAL |
12.176 |
100.00 |
Manual ground skidding (man and gravitation) is applied in small forest holdings for extraction of small amounts of timber over short distances.
Animal ground skidding, mainly by horses is used for pre-skidding for distances between 30 m and 100 m.
Mechanical ground skidding is carried out by tractors of all types. There are 80 000 agricultural tractors with all-wheel drive and approximately 34 000 types of winches, some are also equipped with grapples. They are used in farm forests and sometimes also in big holdings by piece-rate workers and subcontractors. Approximately 300 special forest skidders are part of the equipment of the Federal Forest Estate, big private enterprises and of harvest contractors.
Cable logging by crane has doubled within the last 10 years. Its share has grown to 33 percent in the Federal Forest Estate and up to 75 percent in ownerships of mountainous forests.
Chutes and sledges have lost their significance in mountainous terrain with the development of forest roads. Only pre-logging in thinnings is carried out by loglines (Figure 1).
Figure 1. Leykam logline
Forwarders are increasingly and successfully employed because of their ecological advantages. Their share of logging work is estimated to be 12 percent. Inaccurate feed-back sometimes includes forwarder operations in the mechanical skidding category.
For purposes of damage reduction ground skidding would have to be limited to winter months and dry periods, or else be replaced by cable crane or forwarder operations. Unrestricted entry of machines into stands should be avoided or limited to certain circumstances. Systematic patterns of extraction corridors which are covered by layers of branches are ideal for terrain transport by forwarders. More sophisticated extraction methods would be a considerable asset in reducing damage through timber harvesting.
The objective of mechanising forest work is to increase output and reduce costs. It is more and more important to protect the lives of man and nature as well. Intensive efforts will be necessary to apply ecological techniques on a bigger scale. Examples of such efforts are:
- Careful opening-up of forests by forest roads and tending tracks requiring little space (study of alternative routes and construction by excavator).
- Adoption of fuels with low exhaust damage (bio-fuels instead of mineral fuels).
- Reduced fuel consumption by technically improved machines, smaller skidding distances and more careful planning and organization of the working cycle.
- Least possible damage to soil, stand and timber by good planning and organization of time and location (winter work, branch layers on corridors).
- Early concern for timber quality in tending measures and selective cuts, potential cost reduction by taking all requirements and conditions of the cutting location into consideration.
- EDP-supported function sheets worked out to plan cutting cycles, together with terrain models, business plans, optimum machinery and devices (accessibility sheets are being prepared by the Federal Forest estate and by civil engineers). Function sheets could contain the limits of accessibility for individual machines as well as listing timber species, geological substructure, characteristics of the stand, slope inclination, extraction techniques and other features of the cutting site. Collecting such data means best possible preparation of working systems and working methods. There is a wide range of such systems and methods suitable for small holdings as well as for big forest enterprises.
3. WORKING SYSTEMS - WORKING METHODS
Working systems include the sensible coordination of man, machinery and material to achieve certain work objectives.
Working methods are the type of technique applied to obtain a certain result by means of machinery and device and with a view to the condition of the timber to be harvested.
The working procedure is the sequence of individual operations in terms of space and time.
The working mode explains how and by what means individual parts of the overall work are carried out.
The working manner is characterized by a worker's specific way to carry out an individual operation within a pre-set working mode programme. Based on personal experience, the worker can display know-how, performance and standard.
Timber is extracted by non-, partly, highly-, and fully-mechanized working systems. Three working methods are used: assortment, full-length, and full-tree method.
Non-mechanized timber extraction (assortment method, in small diameter woods also full-length method): The trees are felled and converted manually and by means of power saw. Timber is transported manually, by animal skidding or by log-line.
Partial mechanization (full-length method, occasional assortment method): Felling and upside delimbing are done by power saw; timber is extracted by tractor or cable to the road where final delimbing, measuring and conversion are carried out.
Highly-mechanized extraction (full-tree method): Felling is done by power saw; full trees with branches are moved (possibly after topping) to the forest road by skidder or cable device. A processor is used for delimbing, measuring, conversion into assortments and pre-stacking.
Fully-mechanized extraction (assortment method, occasional full-length method): The harvester, a multi-purpose machine, carries out felling, pre-skidding, delimbing, measuring, conversion, sorting and stacking along the skidding corridor. A forwarder is used to skid the timber to the forest road.
Figure 2. A harvester works together with a forwarder on skidding corridors (SC), covered with branches.
Small forest owners employ non-mechanized and partly-mechanized working methods. The timber is preferably extracted by assortment and full-length methods.
Occasionally, the full-tree method is applied, mainly in small diameter stands of farm forests, provided that the use of a tractor-based processor is economical.
The state-of-the-art is fully-mechanized timber extraction causing least possible damage to soil and remaining stand. It is suitable for gradients up to 35 percent and in deciduous forests up to 40 cm breast height diameter (BHD). For higher gradients, highly-mechanized cable devices are the only means to reduce damage to soil and stand. Subsequent conversion is carried out by a processor. Harvesters mounted on semi-legged vehicles have been used but are still in their testing stage.
4. EXAMPLES OF ECOLOGICAL MECHANIZATION IN LARGE FOREST-HOLDINGS
Decisive factors for mechanical harvesting in large forest estates are as follows:
- all-year operation;
- all-weather operation;
- separate working sites for winter and summer;
- terrains reserved for skidder and cable operations;
- choice of terrain for uphill and downhill logging; and
- clearly defined management strategies and work-force conditions.
In view of the present situation of many forest holdings, some parts of the forest are likely to be altogether excluded from the cutting cycle. Function sheets are important instruments for the appropriate selection of cutting sites.
4.1 Skidder terrain
There are numerous well-known harvesting methods for skidder terrain, of which the following are ecologically favourable:
Harvester and Forwarder: Combined they are suitable for thinnings, single-stem and final cuts of trees up to a BHD of 40 cm. This system causes little damage since skidding corridors can be covered with branches. Damage to remaining trees is recorded to be up to 2 percent. It is by far the most economical system presently known (output approximately 15 m3 in bark/hour). (Figure 2)
Power saw and forwarder: Applicable for clearing of natural regenerations, single-stem cutting and thinning. Trees are felled perpendicular to the skidding corridor and crosscut within the reach of the hydraulic loading crane of the forwarder. More distant trees (up to 2/3 of a tree-length) are felled towards the corridor, delimbed, pulled to the forwarder by crane, where they are crosscut and loaded. With a crane-reach of 11 m, the forwarder can pick up individual trees from natural regeneration and cause very little damage to the surrounding stand. Removal of the stems remaining from the old generation is followed by stem rate reduction, for which damaged trees are picked out first (output 8 to 25 m3 in bark/hour, on an average 12 m3 in bark/hour). (Figure 4)
Power saw and clam-bunk skidder: Suitable in natural regenerations for longwood conversion. The trees are felled towards the skidding corridor, subsequently delimbed and converted into logs of up to 14 m. The skidder's crane loads the assortments onto the clam-bunk of the skidder. Modern forest skidders with low-pressure tires and 3 to 4 axles apply least possible pressure to the ground and keep damage to a minimum (output 14 to 25 m3 in bark/hour, on an average 18 m3 in bark/hour).
4.2 Cable terrain
Winched articulated skidders and all-wheel drive tractors with bogies or cable winches and radio-control are only used ecologically if they operate on frozen soil with snow cover. Mobile cable devices (collapsible tower cranes) are largely in line with modern ecological requirements and cause little damage if they are applied appropriately.
Combined cable devices are increasingly used and are the most economical alternative in mountainous terrain. The most advanced development is presently a collapsible tower device with loading crane and processor head (OEBF Mauko - developed by the Austrian Federal Forest Enterprise - with PKM 6, and Wanderfalke combined with KP40). Additional combinations are collapsible towers with loading crane and grapple yarder, collapsible tower bogie with sledge winch (Hollenburg) or collapsible tower device combined with lateral skidder, radio control and operator to attach the load (Hespamat).
Sledge winch - cable devices for gravitation and/or all-terrain operation are ecologically favourable systems if the timber is freely-suspended during extraction. It helps to reduce costs to lay out half of the skidding corridor above the road and half of it below.
Autocrane and processor: For certain cases, i.e., windfall areas, extraction by means of autocrane is very appropriate because of its accurate way of operating. With a reach of approximately 100 m on clearings and approximately 60 m in stands, the crane's output amounts to 15 - 20 m3 in bark/hour.
Woodliner: This recent Austrian development consists of a radio-controlled carriage with integrated diesel engine. It only requires a skyline and can be driven uphill or downhill, as required. Output in its testing stage has been approximately 6-8 m3 in bark/hour. Its reach is similar to traditional cable crane devices.
Operation by cable device is ecologically favourable because the load is lifted directly from the felling site. Cable operations save energy by not consuming it for the transport of the device's dead weight, but only to drive carriage and load. Nevertheless, cable extraction costs more than other comparable methods since it requires assembly work and well-trained staff.
Semi-legged vehicles with harvester head would be suitable for higher gradients. Practical experience has, however, been limited to some testing operations.
Helicopter extraction causes least damage to soil, stand and environment. In view of its high cost, it can, however, only be used in very special cases.
5. SMALL FOREST OWNERSHIP AND FOREST TECHNOLOGY
In small forests the owner is at the same time concerned with planning, organization and work execution of timber harvesting. Before work can start, long-term developments as well as criteria of planning and organization will have to be considered. In general, farmers owning forests will be used to this decision-making process since it is common also in agriculture. Occasional gaps in the knowledge of forestry can be filled by consultants and further training.
Characteristics of small holdings
Small forest holdings owned by farmers are characterized by:
- interrupted cutting cycles;
- seasonal operations, e.g., autumn - winter;
- fine-weather operations;
- limited capacities for work and equipment;
- basic equipment, tractor and power saw with low utilization;
- forest work as a secondary activity;
- management and execution of work resting with one and the same person; and
- increasing number of forest owners who are not trained foresters.
5.1 Mechanization in small holdings
As compared to Sweden, where special small equipment has been developed for small forest owners, Austrian forest experts believe that mechanization in small forest holdings should be based on tractor and power saw. To put tractor capacities to better use, tractor attachments would have to be designed, produced and used. The major share of extraction in farm forests is carried out by tractors to which winches are attached or mounted. The timber is more or less logged along the ground.
If logging is carried out in winter on frozen soil and snow cover, it will cause little ecological damage. There are, however, frequent operations in thawing weather or on soft soil which affect soil and stand to a relatively large extent. If damage is to be kept to a minimum, ground skidding should be limited to pre-skidding by machines that stay along skidding tracks or corridors.
Main extraction is better done by cranes mounted on trailers, their advantages being almost as numerous as those of the forwarder. Crane trailers could reach bigger landings, from which more timber could be sold cooperatively. On dry and accessible ground, the employment of tractors with grapples would be as ecological and economical, if further conversion is carried out by processor mounted on tractors.
Horse skidding should be limited to pre-skidding and distances between 30 and 100 m. Additional equipment, such as skidding pans and crane bogies, should be used to avoid damage to the soil.
In cable terrain there are a series of ecological methods for small forest holdings, from tractors with radio-controlled winches to double-drum cable winches with tower or even collapsible towers.
Radio-controlled winches help to extract timber very carefully, since the load is accompanied and obstacles can be avoided. Special operations for small volumes can be carried out by radio-controlled winches.
Figure 3. Cable extraction in small forests by means of a small mobile cable system consisting of a tower attachment, mainline, and haulback line and simple carriage.
Double drum winches can carry a mainline and a haulback line with a pulley. Distances of up to 120 m can be covered. Manually pulling out the mainline is not required.
Tower attachment with mainline and haulback line as well as carriage can work on distances of up to 250 m on concave terrain. (Figure 3, high lead system)
Tractors with simple tower cable devices are used for uphill and downhill yarding. To ensure profitability a supply of approximately 25 m3 of timber is required for each corridor, if connecting corridors are available.
In order to work in small holdings ecologically and at low costs, skidders have to be gradually replaced by hauling cranes mounted on trailers. In cable terrain, the raised-head method and fully-suspended extraction would be suitable. Traditional farming experience should be adopted and sustained yield become the principle to preserve economic resources in the mountains. Of all Alpine countries, Austria has the biggest share of mountain farmers even if there are other countries in the Alps with more extreme mountain farming conditions. The objective of mountain forestry is therefore to find efficient methods for its management.
6. FOREST TECHNOLOGY IN BIOLOGICAL PRODUCTION
In 1980, a change in ecological thinking was noted among Austrian forest economists. Although ecological principles had been discussed for decades and occasionally been put into practice, it was only around that year that natural regeneration and nature-related management were revived. Regarding technical support of natural regeneration, there is a deficiency of knowledge but an increasing curiosity among Austrian silviculturists.
Soil scarification to promote natural regeneration has been a well-known silvicultural measure among foresters. But apart from damage caused by skidding or by forest road construction, there is hardly any soil treatment for better regeneration. Fifty years ago it was a traditional technique to prepare the soil for regeneration before a seed year. Knowledge and skills seem to have been forgotten and findings by neighbouring countries reach Austria only gradually.
Literature offers guidance on soil treatment only for regeneration of certain species, such as beech and pine. There is little material on other species in this context.
Approximately 130 years ago better machines and methods were developed in Germany, Denmark, Sweden and Finland in order to promote natural regeneration of mainly beech and pine. All these tools (forest strip plow, cultivator, harrow) were first designed for animal traction. Increased mechanization after the Second World War also included devices for soil preparation, making them mainly heavier and in part more efficient. These machines and devices are, however, designed mainly for flat areas and for terrain accessible by skidder. For higher gradients, the development is just about to begin.
Scarification by machines seems a desired development, because generally cuttings are most frequently carried out on small areas and by single stem extraction. Therefore, in most cases natural regeneration is the logical expectation. Artificial influence has increased the number of sprouts and has improved physical and chemical soil qualities. There is better contact between mineral soil, humus and seed. Several factors affecting germination were eliminated, sticking of seeds in weed flora is getting rare, and late frosts do not have their detrimental effects.
Regeneration periods can be considerably shortened because, by better planning, the regeneration cycle can be completed in one year only. The best period for mechanical scarification is between late August and the first frost or snowfall. Detailed work planning and instruction of workers is as important as visible marking of work areas by sawdust or vanes in order not to damage existing regeneration.
Well-planned and organized scarification helps to make better use of nurse years, vertical growth of plantlets will be more uniform and the growth cover will be without major gaps. Since timber extraction in natural regenerations is known to be cost-intensive and may cause considerable damage, planning, organization and execution of work have to be well-prepared and professional. Dense and uniform regeneration makes all further work easier and the removal of stems remaining from the old generation can start quite early.
To clear regenerations motor-manual methods together with forwarder or hydraulic bundler have been efficient in skidder terrain. In cable terrain, motor-manual felling precedes extraction by cable crane, autocrane or special cable devices.
It is, in any case, important to clearly lay out skidding corridors in the terrain. In skidder terrain, trees are felled perpendicular to the corridor. In cable terrain, the assortment method requires uphill felling at an acute angle to make lateral haulage to the mainline possible without changing the direction of logs. After skidding is completed, the branches are piled up if necessary. At the same time, stem rates are reduced by picking out damaged stems first and trying to put some space between the trees. Proper choice of weather and season may reduce the hazard of insects.
Figure 4. Clearing natural regenerations by forwarder (Trzesniowski 1994)
Machines, devices and methods for soil scarification
Figure 5. Survey of methods for treatment of natural regeneration and preparation of soil (according to Jungwirth, 1992, revised)
Of all possible methods for preparing the soil for natural regeneration (Figure 5) the use of machines has proved suitable for flat areas and motor-manual methods have been successful on slopes; for skidder terrain, there is a series of machines, such as disk plow, disk harrow, grubber, share plow, tractor-attached rotary cutter, excavator and special pusher.
For higher gradients power saw drill, mini-cutter, one-axle skidder and special clear cutter can be chosen. Semi-legged vehicles are still in their testing stage. In flat areas, scarification is applied in patches or strips; on slopes only small sections are prepared. Devices used in agriculture and adapted by forestry can cover large areas in a short time and can therefore be used economically. The disk harrow is a most economical device since its cutting depth is small and it can be pulled by light machines. Whereas the choice is big for flat areas, it is very small for slopes. Power saw drill, mini-cutters and one-axle skidders seem to be blocked in their development and their employment is restricted to individual cases. Scarification by semi-legged vehicles has to be further tested to yield any practicable results.
7. SUMMARY
Forests and their utilization have traditionally had a high significance for human life. It was first a means to meet basic needs. Later, mining required cuttings that exceeded personal need and forest work had to become systematic. Exploitation and scarcity of timber led to strict regulations and enforced forestation. Sustained yield became the principle of timber extraction and was first mentioned by Carlowitz (1713) in forest literature.
Decades passed without major changes in forest work. Methods were handed down from generation to generation without much creative thinking. "Work" came to be considered as a factor of production after 1926, and the influence of systematic training on output was only realized after the Second World War. New tools (rake tooth saws) were invented, the one-man power saw was introduced and new work systems, procedures and methods changed forest work into forest technology. Increasing wages were accompanied by shorter working hours. In the long run, single-stem cuttings and a high supply of timber through disasters could not prevent costs of timber extraction from decreasing, thereby keeping up the productivity of the forest economy.
The most important investment for economical timber harvesting is the opening-up of forests.
In addition to increased outputs and reduced costs, it is now of utmost importance to reduce energy consumption of machines and to introduce ecological fuels. Future improvements will concentrate on reduced damage to soil, stand and timber and on EDP-based function and accessibility charts. Efforts will have to be made to select work systems and procedures with a view to professional principles, existing terrain requirements and to neighbouring areas as well.
Along with mechanized extraction new technologies in biological production should receive more attention. Single-stem cuttings as a consequence of diseases and disasters require subsequent low-cost afforestation. One way to promote the growth of stable forests which are in line with local conditions is artificial soil scarification. Such forests will have lower rotation and production times and will therefore be more economical. In order to avoid negative side-effects of scarification, expert knowledge on causes and effects is necessary. Forest technology will therefore have to be coupled with respective studies on growing site characteristics.
Modern leadership should promote personal responsibility and make creativity possible. Forest technology must be further developed by reasonable research in order to progress. In this context, joint efforts between forest owners, researchers and industry is as important as systematic post-graduate training of all staff.
