Abstract: Sustainable forest management practices frequently confront the tension between economic viability and conservation objectives, particularly where forests occur in environmentally sensitive zones. The use of skidders in protected areas is an essential solution for enabling timber harvesting in environments where the establishment of new skidding trails is either prohibited or highly restricted. These machines are the most used timber extraction machines in Central and Eastern Europe, and cable/adapted skidders are used to increase productivity and to reduce labor. This study compared the work cycles, productivity and costs of four types of skidders working in similar coniferous stands: a dedicated cable skidder, a dedicated cable-grapple skidder, a dedicated grapple skidder and an adapted skidder. The comparison of delay-free work cycles of the four skidders showed the largest share is occupied by travel loaded. The cable-grapple skidder had the highest average speed of 5.6 km h−1, followed by the grapple skidder at 3.97 km h⁻¹, the cable skidder at 3.79 km h⁻¹, and the adapted skidder with an average speed of 3.31 km h⁻¹. The average delay-free productivity of the study skidders is highest for the adapted skidder, followed by the grapple skidder with a slightly lower rate, the cable-grapple skidder, and the cable skidder. In conclusion, the average payload of the grapple skidder and the cable grapple skidder is less than the maximum payload of the machine. This is due to the narrow skidding roads and because these skidders are not suitable for the specific site-selective felling with marked single and small groups of trees. The dedicated cable skidders and the adapted cable skidder are very close in productivity. The average productivity of dedicated cable skidders was 17.7 m³ h⁻¹, while the productivity of the adapted skidder is 14.5 m³ h⁻¹. Considering this, adapted skidders could be a good solution for improving economic productivity in sensitive forests.

Key words: Natura 2000, Sustainable forest management, Forest operations, Productivity and costs