The significance of above-ground biomass, moisture content and mechanical properties of peat layer on the bearing capacity of ditched pine bogs

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The Effect of Wider Logging Trails on Rut Formations in the Harvesting of Peatland Forests

Peatlands are very problematic from the bearing capacity point of view. Therefore, logging activities on peatlands in Finland are mainly carried out during the coldest weeks in winter time. More intensive utilisation of peatland forests requires logging activities to be increasingly carried out during unfrozen conditions. Multiple passages of a harvester and a loaded forwarder used for the transportation of timber cause deep ruts on the forest floor. Wider logging trails have been presented as an interesting approach to increasing the number of forwarder passages along a single loggingt trail. It might be advantageous not to follow the same ruts on each pass but to choose a new parallel route, so that new ruts are formed alongside the previous ones. The study aimed at investigating whether it is beneficial to use wide trails in reducing rutting in forests growing on drained peatland. Field studies were conducted on a drained peatland in Alkkia experimental forest, located in Karvia in Western Finland. In the driving test, a forwarder was driven in the same forest site on logging trails with widths of 4.5 m, 6 m and 10 m. The results indicate that wider logging trails provide the forwarder driver with opportunities to reduce rutting in peatland forests

Performance of weather parameters in predicting growing season water table depth variations on drained forested peatlands – a case study from southern Finland

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Soil disturbance by cut-to-length machinery on midgrained soils

Article id 10134201

Impacts of timber forwarding on physical properties of forest soils in southern Finland

Forest harvesting activities can cause soil damage and disturbance through soil compaction, rut formation and soil mixing. These affect the soil structure and functions and forest productivity. Soil compaction results for instance in increased bulk density and decreased porosity, affecting soil moisture, water infiltration and aeration. The effects of timber forwarding on soil physical properties have gained little attention in boreal forests. These issues will become more important in the future since harvesting operations on unfrozen soils are getting more common due to the anticipated climate warming. In this study, changes of forest soil physical properties (bulk density, moisture content and porosity) after 1-10 forwarder passes on two fine-grained mineral soil sites in southern Finland were analysed. Penetration resistance and rut formation were also measured. The measurements were performed in three periods with different soil moisture conditions. The test drives were carried out with a conventional 8-wheeled forwarder with total mass of 29.8 tons. Soil bulk density increased and porosity decreased after the machinery passes. However, soil moisture content increased on one site and mainly decreased on another. The first three passes caused the greatest compaction and rutting, the first pass having the strongest impact. After the first and third pass 34-55% and over 70% of the total mean rut depth was formed, respectively. Further passes caused only minor rutting. The compaction and changes of soil physical properties appeared to be greater in dry conditions. Rut formation and soil mixing were greater in moist conditions. The results are, however, site-specific, and more research is needed to achieve a better understanding of the relationships between different factors affecting impacts of timber forwarding on soil.Peer reviewe