Möglichkeiten der hoch- und vollmechanisierten Holzernte in der Durchforstung unter Berücksichtigung technischer, wirtschaftlicher und ökologischer Aspekte

Wien

1992

274 S.

Serie

8879

400092952

The presented study shows today's possibilities of mechanized thinning operations with regard to technology, environment and economics. After a review of the different timber harvesting systems in the world the central euripean methods where marked out. The technical limitations of different machines for thinning operations were specified. The study encloses small and large scale technologies from processors mounted on the three point lift up to one-grip harvesters. The performance of the different machine groups were observed by time studies. With help of the calculated cycle times the performance under different site and stand conditions can be predicted. The knowledge of the performance is the base for cost-calculations, for comparisons between the different machines and investment calculations. When slopes doesn't exceed 35% and the ground roughness allows driving with a wheeled carrier, the best economic results are caused by one-grip harvesters. Also the number of stand damages is below the damages caused by other technologies. The tractormounted processors have a lower investment level but the timber harvesting costs are still higher because of the percentage of manual work. In the slope class above 35% costs are increasing. The combination of a crane processor and a yarder mounted on a truck represents the most advanced technology in steep slopes. But also in this case the harvesting costs increase because of the high percentage of manual work. Further reflexions in machines for steep slopes should be done to reduce the difference between timber harvesting costs in flat areas and steep slopes. With regard to the performance of the different machine groups the investment planing process was discussed. After comparisons of performance and costs the most advantageous alternatives were marked out. The profitable technology was searched by dynamic investment calculations. The one-grip harvester has the highest return of investment. The labour costs influence the cost difference between manual and mechanized thinning. To find the best investment decision also the non economic factors were taken into consideration by preparing an analysis of costs and effectiveness.