Özet:

Mechanized harvesting operations yield high productivity; however, it damages forest soils seriously. The objective of this study is to determine the impacts of skidding operations on topsoil physical and chemical properties at four different forest floors (tractor road, skid trail, harvesting area and undisturbed area) after a harvesting season. Also, the relationship between soil compaction and soil moisture of these areas were analysed. Soil compaction was estimated with the values of topsoil penetration resistance on two soil depth layers (0-5 and 5-10 cm). In total, 24 soil samples were taken to the laboratory for some physical and chemical analyses. Three soil moisture levels were delineated for the different forest floor areas ranging from 28% to 54%. Significant negative correlation between penetration resistance and bulk density, soil pH and calcium carbonate and significant positive correlation between penetration resistance and organic C, total N and Corg/Ntotal ratio were found. It was determined that four study sites shared similar features all having heavy clay (53.5-65.2%) soils. According to soil analysis, the lowest bulk density value (0.89 g/cm3) was found in harvesting area and the highest bulk density value (1.15 g/cm3) was found on the tractor road. Also, the highest content of organic C was found on the skid trail as 5.57% and the lowest content of organic C was on the tractor road as 1.52%. As the soil moisture content increases when penetration resistance decreases, mechanized harvesting operations should be arranged according to precipitation and soil moisture.

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