Volume 46 No. 2

Ground-based forest operations can produce an intense level of soil disturbance and hamper the growth of seedlings. However, previous studies on the topic of seedling growth performance on the skid trail network showed high variability and non-uniform responses. Therefore, a multivariate meta-analysis was applied to investigate the effects of soil disturbance after ground-based forest operations on the aboveground and belowground growth of seedlings. We further assessed the effects of the following moderators: type of regeneration, type of stand, number of years since the forest operations, mass of the machine used, number of machine passes in the investigated skid trails, and the increased soil compaction in the skid trails. The results supported our hypothesis that ground-based forest operations had a greater effect on the growth of broadleaf species and natural regeneration. This was, however, mostly true for belowground growth, that was typically more affected than aboveground growth. We discovered that there is a recovery in seedling biomass and lenght following harvesting, but this is a long process that requires about ten to twenty years to begin. We found that the number of machine passes and the machine mass did not directly correspond to a higher level of impact, indicating that the actual disturbance drivers are more complicated interactions that occur among the machine, the way in which forest operations are carried out, and the soil properties. It was finally demonstrated that soil compaction was the primary cause of disturbance to seedling growth, primarily affecting belowground biomass and lenght. In particular, we identified a minimum threshold of a 30% increase in soil bulk density to observe statistically significant negative effects on seedling belowground growth. Soil compaction proved to be the main factor that can jeopardize the development of forest regeneration in the skid trails. This suggests that the same best management practices that are used to reduce soil compaction caused by machinery should also be used to reduce the detrimental effects of ground-based forest operations on seedling development. As future research directions, long-term studies are recommended to assess the recovery process dynamics. Moreover, more research on broadleaf, natural regeneration, and Cut-to-Length machinery is strongly suggested.

The substitution of petrol-powered chainsaws with battery-powered ones has still not taken place in professional forestry. With the latest battery-powered chainsaws, performance is not an issue anymore, but energy storage and recharging still are. Nevertheless, there are some ergonomic points where battery-powered chainsaws tower over petrol-powered ones. This work aims to measure, evaluate, and compare hand-arm vibration between two comparable chainsaws, one petrol, and the other battery-powered. Stihl MS 261 C-M and Stihl MSA 300 C were chosen for this task. The cutting measurement was performed on a wet trunk of sessile oak (Quercus petraea) with a diameter of 30 cm, and on thinner branches (<7 cm) in the canopy at the same felled tree. Time data that represents the ratio of chainsaw handling elements within effective working time in cutting and processing was obtained from previous research. Vibration magnitude was measured in compliance with ISO 8041-1:2017, ISO 5349-1:2001, and ISO 5349-2:2001 standards. The results regarding vibration total value (ahv), daily vibration exposure (A(8)), and time to reach exposure action value (EAV) and exposure limit value (ELV) proposed by EU Directive 2002/44/EC imply higher magnitudes on the rear handle and higher exposure of the right hand for both types of chainsaws. For petrol-powered chainsaw, results for measured vibration magnitude are 4.13 m/s2 for the left hand, 4.72 m/s2 for the right hand, and for battery-powered chainsaw 2.18 m/s2 for the left hand, and 2.82 m/s2 for the right hand. Daily vibration exposure is drastically lower when using a battery-powered chainsaw (A(8)=1.2 m/s2 – left, A(8)=1.5 m/s2 – right), likewise, the time to reach EAV and ELV is many times longer. The current state legislative restriction (Ordinance on Occupational Safety and Health in Forestry 1986) should be revised with the aim of increasing the effective working time because, according to the results of this work, it would be justified.