Fully mechanised timber harvesting in cut−to−length method (CTL) has a number of advantages compared to tree−length (TL) and whole tree method (WT), including lowering unit costs, increasing productivity and reducing or even eliminating heavy manual labour. The demographic changes we are seeing, and thus the expectations of the workforce and competition in the labour market, mean that fully mechanised work or automation will be essential in the future. The aim of this article is to analyse the damage to remaining trees in the stand and the efficiency of the work in relation to the width of the skid trails (narrow 2.7 m and wide 3.5 m). Analyses were carried out during the first thinning cuts in a 25−year−old pine stand with so− called industrial wood. A small tracked excavator equipped with a harvester head was used in the experimental plots. The efficiency of the work is influenced by the volume of a single tree, the thinning intensity and the stand density. The same variables also determine the effect on the amount of damage in the stand remaining. The parameters characterising the damage to the trees remaining in the stand indicate the occurrence of significantly longer wounds in the sample plots with wide access trails and a higher total area of wounds (+40%) compared to the damage observed in the sample plots with narrow access trails. From the results obtained, it can also be assumed that the very serious damage, deep injures in the wood of trunk and root amputation are random and do not depend on the width of the trails. The results show the importance of choosing the right machine to facilitate work in dense stands. The observed wounds according to Meyer’s tree damage classification do not allow statis− tically significant differences between damage occurring with both narrow and wide skid trails. However, any bark damage and other damage to tree trunks increases the risk of head rot and thus significantly reduces the future potential for top quality timber. Narrow skid trails reduce non−productive areas and simultaneously increase the difficulty of mechanical thinning. However, when using wide skid trails (3.5 m), a higher operating efficiency of approximately 12% was observed.

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