Impact Assessment of Timber Extraction to Residual Stand in Natural Managed Forests

Damage to the trees left behind after thinning is a consequence of any harvesting activity and may include root abrasion and breakage, bole wounds, and broken branches and crowns. The objective of this study was to study the effect of ground skidding system on forest regeneration and residual stand in natural managed forests. This study was carried out in compartments no. 305, 306 and 309 of Gorazbon district, in Kheyrud forest. In this study the extent of damage to regeneration and residual stand have been determined using full inventories of damage along skid trails in the three compartments. Results showed that the most of damage were occurred to the small sapling and sapling, and broken and wounded were the most types of damage in regeneration. The majority of the damage occurred in two 40-20 and 70-40 cm diameter classes and the most of the wounds were superficial. Fifty percent of all scars found were larger than 500 cm2 in all species and more than 90% of the damage on a tree occurred within 1 m of ground level and located on the tree roots. The results showed that the most of the damages also occurred within 1 m of the skidder centerline. Tree location appears to have an influence on both scar height and the number of scars a tree may receive. Therefore, efforts to reduce residual damage should be focused on protecting the trees located near skid trails and the first 1 m of the bole, where the likelihood of wood decay is greatest.