Intensive forestry operations may cause soil compaction, plastic soil disturbances and rutting, which are responsible for undesirable effects on soils, vegetation and water bodies. Despite the numerous studies aimed to identify the main factors affecting soil damages, it still remains unclear whether wood extraction methods and driving direction (uphill or downhill) may affect the impacts of forest machines. This research analyses soil compaction and soil penetration resistance as well as rutting from forwarding and skidding using the same farm tractor in up- and downhill wood extraction. Rutting was estimated by 3D soil reconstruction derived by portable laser scanning (PLS) and close-range photogrammetry using structure for motion (SfM). Our findings showed that the direction of extraction did not affect soil damage severity during forwarding on a 25% slope. On the contrary, in order to reduce soil compaction, downhill skidding is preferable to uphill skidding. The results showed that the pressure on the ground caused by vehicles can be distributed horizontally, thus affecting also the soil between the wheel tracks. The soil bulk density inside the tracks after 10 forwarding passes increased by 40% and with 23% between the wheel tracks. The soil displacement in skidding trails (7.36 m3 per 100 m of trail) was significantly higher than in forwarding (1.68 m3 per 100 m of trail). The rutting estimation showed no significant difference between the PLS and SfM methods, even comparing the two digital surface models (DSMs) obtained, even if photogrammetry was preferred for technical and practical reasons.
The use of battery tools is very common in many fields of work. In fact, the electric engine and batteries have several advantages over traditional endothermic engines, including low emissions, in terms of pollutants, vibration and noise. In this context, the chainsaw market started producing electric models powered by batteries. These machines can be useful in forestry, but information on their performance is scarce. The aim of this work was to compare the performance, in terms of cutting times, of three Stihl chainsaw models: the MS 220C-B (battery powered), and the MS 201 C-M and MS 261 C-M (both petrol powered). The study was carried out on five different wood species, also taking into consideration the presence/absence of wood defects in the cutting. More than 800 cuts on 15 m × 15 cm wood beams were video recorded, and the cutting times were later obtained to a resolution of 4/100 of a sec, using video-editing software. The results showed a poorer performance of the battery chainsaw than the petrol chainsaws, especially on certain wood species. However, this difference has been reduced when compared with older models. In conclusion, battery chainsaws need some additional improvements to be introduced into forestry, but their high potential is evident.
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