Influence of the logging season on the condition of topsoil layers

Abstract

Proper management at the stage of forest utilization should take into account the need to protect soils, and one of its forms is timber harvesting performed in periods when soil disturbance is least likely. Such conditions occur, inter alia, when the soil is frozen and protected by a layer of snow. The aim of this study was to determine whether topsoil disturbances after timber harvesting in summer and winter seasons differ in terms of quality and dimensions. The study was carried out in southern Poland, in an oak stand which underwent late thinning. Tree felling and delimbing was performed with the use of chainsaws. The harvested timber was extracted with the use of farm tractors, by means of skidding in the case of long logs and by means of forwarding in the case of rollers. The logging tasks were carried out in two periods: in summer and winter, the latter under conditions of temperatures below zero and the presence of the snow cover. Two experimental plots were established in the stand, one located in its fragment used in summer and the other in winter. The plots had the shape of a square with a side of 100 meters. Their area was divided into 100 one-are measurement fields, which were squares with a side of 10 m. After the completion of logging tasks, the dimensions of the resulting soil disturbances were determined at each field. Timber harvesting in winter had a positive impact on the protection of topsoil layers. The share of disturbed soil was lower (0.6%) on the plot where felling had been performed in winter as compared to summer felling (2.6%). The area, volume and depth of soil disturbances were statistically significantly higher after timber harvesting in the summer period. Timber harvesting in the winter period resulted in the soil condition undisturbed in 70% whereas in the summer season it was about 40%.