Environmental Impact of Timber Extraction on Forest Soil Disturbance and Penetration Resistance in Kheyrud Forest

The concern over soil compaction, displacement, visual disturbance, and long-term site productivity has intensified in recent years. The use of mechanized equipment to extract timber in harvesting operations influences soil conditions. This study investigated soil disturbance from an integrated forest harvesting/ traditional logging system operation on a mixed broadleaved stand in compartment No. 223 in Namkhaneh district in Kheyrud forest. The objective of this study was to assess soil disturbance from an integrated forest harvesting and traditional logging system operations. Statistically significant changes in penetration resistance at various depths below the soil surface and changes in penetration resistance related to visual soil disturbance. The level of penetration resistance at five levels of soil visual disturbance and four soil depths (5, 10, 15, 20cm) were measured. Results indicate that the logging operation contributed to statistically significant soil disturbances. The main effect of soil disturbance and depth classes were statistically significant. This result implies that penetration resistance changes as depth below the soil surface increases. The interaction effect between disturbance class and depth class was statistically significant. This implies that the differences in penetration resistance values between visual disturbance classes depend on depth below the soil surface. Penetration resistance values within each of the five analyzed disturbance classes tend to increase with increasing depth below the soil surface. Based on these results, we concluded that soil disturbance classifications were statistically significant for predicting penetration resistance.