Productivity, Costs and Residual Stand Damage of Timber Harvesting Methods in Scots Pine Stands with Extended Distance Between Skid Trails

In forest operations, economic advantages can be obtained by increasing the distance between the skid trails. This protects soil by reducing the compacted area, while at the same time increasing the productive timber ground area. These advantages are offset by disadvantages, as fully mechanized timber harvesting is not possible and motor-manual felling is required for the areas that cannot be reached by the harvester. This in turn reduces work safety and increases the workload and personnel requirements, possibly leading to higher timber harvesting costs.To analyze the consequences of an extended skid trail distance, a timber harvest under real conditions was carried out in north-eastern Germany in the fall of 2023. In a 72-year-old Scots pine (Pinus sylvestris, L.) stand with an area of 23.2 ha, 692 m³ of wood was harvested in a thinning operation. Three different timber harvesting methods with extended skid trail distances of approx. 40 m (ES) were investigated and compared to a fully mechanized system with conventional skid trail distances of approx. 20 m (CS) in a time study with a total of 150 recorded hours. Following the harvest, the residual stand damage was also recorded.The timber harvesting methods with ES had higher timber harvesting costs than the method with CS, although there are major differences between the three semi-mechanized timber harvesting systems: The productivity of the harvester increases as the number of passes by the harvester decreases (from 13.87 to 14.09 to 15.99 m³/PMH15). Looking at the forwarder productivity, it is higher in ES than in CS. Finally, the costs of the harvesting systems ranged between 29.18 €/m³ for CS to 30.40, 32.41, 34.56 €/m³, respectively, for ES. There is no significant difference in the residual stand damage across the methods. The productivity of semi-mechanized timber harvesting methods can be improved if the motor-manual felling is carried out before the harvester is used and if the trees are not winched with a cable tractor.