Acta Scientiarum Polonorum
Silvarum Colendarum Ratio et Industria Lignaria

Abstract Timber harvesting in Poland is performed with the use of manual and machine techniques with a large dynamic load. The aim of the present research was to analyse the level of energy expenditure in operators who harvest timber in a mountain spruce stand in the forest district of Nowy Targ. The technique under analysis included the performance of logging as part of late thinning with the use of a cable winch propelled by a chain saw engine. The research showed that, in the thinning technique under analysis, the elimination of manual unblocking of trees suspended during their felling increased work safety. The results also show a significant reduction of a chain saw operator’s energy expenditure from 24 kJˇmin-1 to about 17.6 kJˇmin-1. The energy expenditure reduction, which occurred in the thinning of coniferous species by means of a portable cable winch propelled by a chain saw engine, indicates a possibility to increase the humanization of the operators work on the level of manual and mechanical techniques.