Evaluating and comparison of environmental impacts of two logging methods (Case study: Namkhaneh District in Kheyrud Forest)



Hyrcanian (Caspian) Forest in northern Iran with many endemic and endangered species is a rich area for biodiversity. The use of ground-based skidding is well accepted practice for the extraction of timber from the forest, but this has tended to cause the greatest environmental problems. The aim of the study was to evaluate and comparison of environmental impacts, residual stand damage, regeneration, and to quantify these effects such as: extent of the damage, wounding patterns, size and distribution after logging operations that utilized two different methods: short-log and long-log. A Timberjack cable skidder was used and the study location was in the Kheyrud Forest. Post harvesting assessment of damage to the residual stand was compared along skid trail by 100% inventory method and also for the assessment of regeneration damage along winching strips. The results showed that along winching strips the percentage of damage to the regeneration was 44 and 36 %, while the tree damages along skid trails reached 2.3 and 4.1 % in the short- and long-log methods, respectively. The greatest average amount of damage to a bole occurred along the first 1 m up from the ground (97%) and also within 4 m of the skidder centerline (80%). These results clearly show that the short-log method causes less damage to the residual stand than the long-log method. Tree location to the skidder trail appears to have a significant effect on the number and height of scars on a tree. Well designed and constructed trails should be wide enough to allow wood extraction from the forest. Damage to the residual stand might be reduced by proper planning and training of logging crews.