Evaluating the extent, patterns, size and distribution of tree scars following skidding operation (Case study: Kheyrud forest)

The development and deployment of harvesting systems aims to provide physically feasible, environmentally sound and economic solutions. The data of residual stand damage was collected from a mixed broadleaved stand in Kheyrud forest following the cut-to-length harvesting system using Timberjack rubber-tired skidder. After finishing the harvesting operations, damage to the bole, roots, extent of the damage, scars patterns, size and distribution was evaluated for all trees using stratified systematic sampling with a random start and fixed area plots. Results showed that scars occurred on 16.4% of the remaining trees, but the severity of scars varied significantly by species. Forty-six percent of scars for all species was considered as small size (>500cm2). The greatest average amount of damage to the bole occurred along the first 1 m up from the ground (93%) and also within 3 m of the skid trail centerline (86.4%). Gouges were present on 79% of all scars. The stratification of the study unit would effectively improve the accuracy of stand damage surveys.