Soil degradation and wood extraction operations: comparing skidding and forwarding Francesco Neri, Elena Marra, Giovanni Mastrolonardo, Andrea Laschi, Cristiano Foderi, Enrico Marchi

Forest harvesting operations may have a significant impact on soil physical properties. The soil disturbance extent and severity, during wood extraction operations, are related to the condition of the soil, harvesting system. Impacts mainly consists of soil compaction, displacement, and rut formation. Several papers investigate, on the short term period, the soil damages caused by logging operations, but information on the effects of logging on the medium and long term period are still missing, thus highlighting the needs of further investigations on this topic. This study investigates the effects of wood skidding and forwarding on soil degradation on three sites located in Central Italy. Results are related to the medium and to the long term period after logging operations and in details were considered six months, 1 year and 3 years after forest operations. Changes in porosity, bulk density, shear and penetration resistances were investigated on two plots for each wood extraction system adopted (skidding and forwarding). The analysis was conducted using traditional methods (cone penetrometer, steel cylinder and vane test) for evaluating soil damages caused by a loaded forwarder and skidder. The lack or the presence of forest regeneration was also highlighted. After different period from logging operations it was possible to assess that the restoring time of extraction tracks it is related to the previous soil compaction level. Natural regeneration was often observed where the skidder operated and on sandy soils compacted by forwarder machines. In conclusion the effects on soil of forest machines are still present after long term period, thus suggesting that the use of previous tracks must be encouraged to avoid the extension of soil disturbance.