DAMAGE ON STANDING TREES DURING WOOD SKIDDING (WINCHING PHASE) BY CABLE SKIDDER TIMBERJACK 225 A

UDK: 630*37:630*4     Hauling of heavy and voluminous load (wood) partially through forest wastelands and partially on built roads makes this the most expensive phase, which is also technically the most challenging and most damaging for the forest eco-system. Although it is clear that the realisation of this phase in forest harvesting cannot be completed without certain forest damage, in expert and scientific circles there is general consent that by careful planning and execution in forestry, this damage can be brought down to an ‘acceptable’ level.   One of the reliable indicators of stand damage is the amount of mechanical damage resulting from forest harvesting operations. This damage can be ascertained rather easily and correctly, and the environmental and economic consequences of mechanical damage of standing trees are better known than those resulting from damaging saplings or the soil. (Martinić, 2000).  Pertaining to this, this paper presents the measuring and analysis of mechanical damage to standing trees as a result of hauling trees using the cable skidder ‘Timberjack 225 A’ in the forest unit 17,  Management Unit ‘Gornja Stavnja’, Forest Management Company ‘Gornjebosansko’. The amount of damage was analysed, the place where it occurred on the tree, the level of damage and the surface of the inflicted damage. All the stated analyses were carried out for two ways of skidding wood using a winch (falling and ascending).  Results show, among others, that the stand damage expressed in the percentage of damaged trees of the total tree count is 15.41%, which is the upper limit Martinić (1993) ascertained for this phase of forest harvesting, including the variability of working methods and techniques. Almost half of the damage is stated in the first third of the distance between the skidder path and transport boundary, with the largest amount of damage occurring on the most valuable part of the tree (butt end), especially during slope skidding.