W WORKSHOP PROCEEDINGS NEW TRENDS IN WOOD HARVESTING WITH CABLE SYSTEMS FOR SUSTAINABLE FOREST MANAGEMENT IN THE MOUNTAINS

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VIEW OF THE CONTRACTOR FOR FOREST COMPANIES

Anton STREIF, Streif Forest Enterprise, AUSTRIA

Company and operational area

The Streif Forest Enterprise was founded in 1998. A forestry education, four years of practice in the field of timber harvesting and the development of steep terrain harvester technology (mountain harvesters) was the basis for the step into self-employment.

Our working group consists of individual enterprises - each of which is operating its own machine. We have specialized our work on fully-mechanized harvesting systems, as well as on steep terrain harvesting. The annually harvested amount of timber, using mountain harvesters, cable cranes and forwarders is 55 000 m3. Our principals and business partners are big and small private forest owners, small-scale forest owners and Federal forests, as well as wood companies in Austria and Bavaria.

Quality standards for the contractor and general framework of the forest enterprise

The topographic conditions, especially slopes, limit the ability of different harvesting systems.

Required production quantities - transport costs

The ownership structure, especially in small-scale forests, influences significantly the size of the order, which on annual average is approximately 1 200 m3 (solid cubic metres) per operation. This low volume of wood per contract affects the delivery costs: every machine unit (harvester and forwarder) has to change sites 25 to 30 times a year. Consequently the low-boy transportation costs contribute 10 percent of the contract value, not including working time loss and turnover loss.

For the forest enterprise, as well as for contractors, the goal is to strive for greater and economically viable quantities using better industry-wide communication and coordination.

Extraction and traffic ability of steep terrain

Our different types of harvester are in a position to operate on slopes of 0 to approximately 65 percent, depending on soil and weather conditions. The traffic ability of the slope is more a problem for the following extraction. Often it is more the weather that prohibits movement on steep terrain, especially when it should be done without damaging the soil. From past experience, we know that the climbing ability of forwarders is limited to 40 percent depending on soil strength and depth. Slopes greater than 40 percent must be extracted with cable yarders both up- and downhill.

Machine utilization and general framework

The right machine combination is chosen by us to suit the terrain, type of utilization and timber diameter. These criteria, in combination with adherence to delivery dates and sustainable management practices, are further requirements of our principals. We try our best to fulfil these requirements.

The machine's workload depends substantially on wood market conditions in general, price of round timber and industry wood sales. Besides the best possible satisfaction of our principles, these are the most important factors for an optimal, year-round workload of our machines.

As a wood harvesting enterprise in Austria we assume responsibility for compliance with legal regulations, for example clear-cut size, windbreaks or care of work implementation. The reduction of labour and the continual cost pressure on wood harvesting costs increases the demand of contractor's service enterprise. New working fields, such as the increased use of a combination of harvester and cable yarder, in terrain between 40 and 65 percent slopes so far in downhill thinning hardly covers costs. This combination shows rationalization potential: e.g. Harvester Valmet Snake with cable extraction.

Specializing in the “Snake” new harvester technology with cable extraction

The biggest advantage of this system is reduced damage to remaining stands by using the cut-to-length system and the year-round operability.

Downhill cable thinning extraction was reduced or even stopped as a result of technical limitations. On terrain slopes between 40 and 65 percent, cable extraction is a feasible alternative to the forwarder. Thereby, before starting work with the harvester, the cable corridors are laid out in the stand.

The harvester puts the logs (sawlogs and pulpwood) on the harvesting corridor. In this way the logs are bunched under the skyline.

Because of improved concentration of the logs and through reduced lateral yarding distances, the productivity of the subsequent cable yarding is increased. In comparison to motor manual harvesting systems, the bunching of logs is more effective in small diameter stands.

A substantial criterion for the efficient use of this wood harvesting combination is the accumulation of wood in the cable corridor. For economic reasons a minimum of 80 m3 of wood per corridor is required.

The disadvantages of this system can be seen in limited accessibility because of obstacles on the slopes, as well as the compatibility of cable corridors and harvester corridors in rough terrain.

Our strategies for the future

These are some of the strategies we want to implement to the best of our ability in the future:


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