Evaluación del efecto de la extracción de madera sobre la compactación de suelo

Forest logging is the stage of the production cycle in the forest system that causes the greatest impact on the soil, being specifically relevant during primary transport or timber extraction. The general objective of this study was to assess the soil compaction generated by the timber extraction. On the other hand, the specific objectives involved the following: (i) to assess the compaction produced by the traffic of three forwarders (FW) with different wood load capacity and pressure on the soil, and (ii) to assess the effect of consecutive passes of the mentioned machines. The experimental site was set up 26 kilometres away from the north of Nuevo Berlín, Río Negro department, Uruguay, in field belonging to UPM, Forestal Oriental company. An 8-years-old Eucalyptus dunnii stand and 0,24 m3/tree were considered, harvested using the Cut To Length system (CTL). Three FW with wood extraction capacities of 18, 20 and 25 tons, respectively, were assessed, thus generating different pressures on the soil.The resistance to penetration (RP) corrected by the gravimetric soil moisture content was evaluated for the three FW loads, for one, two, and three passes of each. Both the control and the passes were subjected to a previous pass of the harvester machine, at the moment of the stand harvesting. The FW traffic was executed on a type of soil vulnerable to compaction, with a low quantity of organic matter as well as low-moisture content, condition caused by a previous forest fire occurred at the stand. The assessment was carried out immediately after the FW passes. The results obtained show the existence of statistically significant differences between the FW and their load capacity, characterized by higher levels of RP when higher pressures are applied on the soil. However, no significant difference was verified between the number of passes, regardless of their magnitude and load.