Soil and Residual Tree Impacts of a Draft Animal-Logged Timber Harvest Case Study in the Southeastern United States
摘要
Modern ecological forest management often requires low-impact forest operations capable of implementing nuanced prescriptions at a variety of scales. The highly mechanized logging systems that dominate in the southeastern United States are largely incongruous with these criteria, warranting examination of alternative logging systems. Draft animal logging is often touted as a low-impact timber harvesting system, but the ecological impacts of the modern methods utilized in the southeastern US have not been quantified. We conducted a case study on a mule-logged timber harvest that utilized a skid steer to load logs and found that the operation had minor impacts on soil disturbance, soil compaction, and residual trees. Only 6.0% of the study area exhibited soil disturbance, with mule skidding contributing 3.3% and the other 2.8% caused by the skid steer used in the operation. Mule skidding did not have a statistically significant effect on soil bulk density, increasing it by only 3.4% relative to undisturbed soil. The skid steer produced a statistically significant 13.4% increase in soil bulk density. Only 1.6% of residual trees in the study area were damaged by skidding, with an average wound size of 26.8 cm2. The results of this case study indicate that draft animal logging, as currently practiced in the southeastern US, is a relatively low-impact timber harvesting system that preserves the ecological integrity of soils and the residual stand and is suitable to fill the small-volume ecological forest management niche.