Heikkilä, J.Ylimartimo, M. and Mäkinen, P. 2005. Time Consumption, Work Quality and Cost of Mechanised Precommercial Thinning. Baltic Forestry, 11 (1): 73-79

Costs of precommercial thinning (PCT) have increased quite steadily in Finland for a long time. Therefore effective PCT methods must be developed. Although there is still development potential in manual PCT, mechanisation has been considered as a solution to decrease costs of PCT. Machines haven't become common in PCT yet. The most important reason for this is low productivity resulting in high operation costs. If mechanised PCT becomes real business for entrepreneurs and machine manufacturers, technical problems are most likely to be solved. In this study two prototypes of boom-mounted cleaning devices were studied. Prototypes were manufactured by private entrepreneurs. Productivity, work quality and operation costs of these cleaning devices were estimated. Average time consumption of both machines was around 7.5 effective hours/ha in a pine-dominated stand with total density of around 7 000 stems/ha and average cutting diameter of stems around 5 cm. Costs of mechanised PCT in this study were over two times higher than those of manual work.

Key words: mechanised precommercial thinning, cleaning, cleaning device, time study.