Effect of forwarder multipassing on forest soil parameters changes

Abstract

In the lowland part of Croatia, heavy machinery such as forwarders is mainly used for the purpose of extracting wood from even-aged forest stands. According to the forest management plan, forwarders are used intensively in the winter period when the soil is mostly saturated with water and when their activity can cause significant damage to the soil. The aim of this study was to determine changes in soil characteristics as a consequence of the repeated passage of a loaded 8-wheel forwarder on silty clay loam type of soil. The research was conducted in an area where the forwarder usually works and in a way that did not significantly disrupt his normal workflow. The results indicate that during the study period the soil had a good bearing capacity and that the observed changes in soil characteristics (bulk density, total soil porosity, soil moisture, particle density, soil water retention capacity etc.) occurred as a result of breaking structural soil aggregates after soil compaction by multiple passes. Characteristic points (T) of equalized penetration curves indicate the compaction of the soil surface layer. Cone penetration index (CI) values did notshow a proportional increase as the number of forwarder passes increased, although significant differences in their values with respect to the number of passes were found. Shear strength (τ) did not significantly increase with increasing the number of passes, but a statistically significant difference in the measured values was detected at the soil surface, which was not observed at a depth of 15 cm. Exceeding the rut depth limit of 10 cm occurred only after the 20 th pass. Our results indicate that the soil at the harvesting site had a good bearing capacity during the study period.

Impact of MHT9002HV Tracked Harvester on Forest Soil after Logging in Steeply Sloping Terrain

“…A factor that also minimized changes in the physical parameters of the forest floor was the very low moisture content of the forest floor in topsoil SmL1 (39.7%-44.3%) due to high air temperatures at the time of the study reaching 35 • C (the study was performed on 28 July 2020) and the rapid drying associated with the exposure of the area after tree felling. This is similar to the publication presented by Pandur et al [43]. In addition, the protective factor of the soil was the significant amount of needles from the withered spruce trees that were harvested, felling residues after delimbing left by the operator on the machine's route, as well as the remaining organic material included in the fragmentation layer, the thickness of which reached 10 cm, as confirmed by the results of volumetric density measurements (0.52-0.7 g•cm −3 ) (Table 3).…”