Continuous felling of small diameter trees in boom-corridors with a prototype felling head

Abstract

Simulations of the continuous felling of trees in boom-corridors have suggested that it may be possible to increase harvester productivity by a factor of 2.4 when thinning young dense stands. A prototype boom-tip mounted felling head for harvesting in this fashion was therefore built and tested in the field. Using the new head, stands with a density of 10,000 trees ha⁻¹ and a mean diameter at breast height (dbh) of 7 cm were felled at a speed of 0.4 m s⁻¹, with an efficiency of 3.5 s tree⁻¹. The felling speed was limited by the speed of movement of the harvester crane's boom. However, additional tests suggested that the new head could be operated at felling speeds of up to 1.3 m s⁻¹ when cutting trees with dbh values of up to 8 cm. The simulation that prompted this study focused on multiple felling with the crane in continuous motion at speeds of 1 m s⁻¹; the results obtained in this work suggest that the new felling head is capable of sustaining these speeds and so further technical development of the design (e.g. to incorporate accumulating functionality) is warranted.

Keywords:

• Early thinnings
• fuel wood
• geometric thinning
• pre-commercial thinning
• time consumption

Acknowledgements

This study was financed by the “Botnia-Atlantica (Forest Power)” and “Efficient Forest Fuel Supply Systems (ESS)” research programs, and the forest company Sveaskog.