Epsilon Archive for Student Projects

Abstract

The annual demands for forest fuels increases in Sweden. At present, large unutilized biomass resources is found in young, dense forests from which about five million oven-dry tonnes (ODt) (23 TWh) could annually be extracted as forest fuel. But harvesting small trees give high logging costs and new cost-efficient harvesting techniques are therefore required.

The aim was to study the productivity of Vimek 608 BioCombi in forest fuel thinning of Lodgepole pine and to calculate the economy of the harvesting and estimate the thinning quality. The time study was performed in Åmarken in the county of Västerbotten. The study area had 4724 trees/ha with an average tree volume of 26.6 dm3 (on bark).

On average, 15.3 ODt/ha and 1614 trees/ha was harvested. The thinning intensity of the initial basal area was 34%, and 12% of the remaining trees had stem damages. At 100 m forwarding distance the hourly effective work time (E0-hour) consumption per ha was 17.6 giving a productivity of 0.88 ODt/E0-hour. The productivity was influenced by forwarding distance, the harvested biomass/ha, tree volume and the proportion of Lodgepole pine of harvested biomass. At machine cost of 550 SEK/E0-hour, a forest fuel prize of 210 SEK/m3solid, a forwarding distance of 100 m, a productivity of 0.88 ODt/E0-hour and harvested tree size of 19 dm3solid the profitability was -1 633 SEK/ha. The BioCombi is a relative new machine on the market and development of both technology and work methods are possible to increase efficiency, and thus reduce logging costs.