Timber extraction is a time-consuming and difficult stage of producing the wood-based forest products, involving economic and ecological sensitivity. In this study, it was aimed to determine the optimum extraction methods in terms of productivity and environmental effects by integrating the analytical hierarchy process (AHP) method with geographic information systems (GIS). The study was implemented in the coniferous stands located within the borders of Baharlar Forest Enterprise Chief (FEC) in Ayvac & imath;k Forest Enterprise Directorate (FED) in Bal & imath;kesir in T & uuml;rkiye. The main criteria in AHP were slope, skidding (transporting) distance, soil factor, stand age and yield. In the study, tractor skidding, tractor winching, chute system and skyline yarding methods were evaluated by considering environmental effects including residual tree damage and potential impacts on forest soil. In the solution phase, a total of eight suitability maps were produced for four extraction methods for productivity and environmental effects assessment. After the suitability maps were generated, digital data layers of working time were produced for each extraction method using equations about machine working times obtained from previous studies. As a result of the study, it was determined that skidding distance and slope were the criteria with the highest impact in almost all extraction methods for productivity and environmental aspects. In tractor skidding, it was found that soil factor and skidding distance have the highest impact in terms of environmental effects. When considering productivity, the results showed that the most commonly preferred extraction method was the tractor winching (43.30%), followed by the tractor skidding (25.34%). While the chute system was preferred in approximately 20.92% of the area, the least preferred method was the skyline yarding (10.44%). When evaluated in terms of environmental effects, it was determined that tractor skidding (34.02%) was widely preferred, followed by chute system (26.95%), tractor winching (20.96%) and skyline yarding (18.07%).

The extraction of timber is expensive, energy intensive, and potentially damaging to the forest soil. Machine development aims to mitigate risks for environmental impact and decrease energy consumption while maintaining or increasing cost efficiency. The development of rubber-tracked forwarders has gained renewed interest, not least due to climate change leading to unreliable weather in combination with low tolerance for soil damage. The increased cost of rubber tracks compared to wheels is believed to be compensated by higher driving speed enabled by semi-active suspension. Thus, the aim of this study was to theoretically investigate how the productivity and cost efficiency of rubber-tracked forwarders are affected by variations in driving speed and machine costs. The calculations were made with fixed stand parameters, to evaluate performance in well-defined working conditions, and with parameters from 2500 final felling stands in central Sweden, to evaluate performance in varied working conditions. Scenarios were compared to a baseline corresponding to mid-sized wheeled forwarders. The results show higher productivity with the increased driving speed enabled by rubber tracks and suspension at all extraction distances, with larger differences at long extraction distances. Assuming a 15% higher machine price for the rubber-tracked forwarder and a variable cost increase proportional to speed increase, extraction costs break even with the baseline at 400 m and 700 m extraction distance for moderate and fast driving speed, respectively. Furthermore, a rubber-tracked forwarder is likely to enable access to a larger part of the harvest area during longer seasons. For the studied set of stands, the year-round accessible volumes are estimated to increase from 9% to 92% with a rubber-tracked forwarder. With rubber tracks instead of wheels, good accessibility has the potential to be combined with low soil impact and cost efficiency in a favourable way for both industry and ecosystem.