Productivity of integrated harvesting of pulpwood and energy wood in first commercial thinnings
The aim of this study was to quantify the productivity and the costs of different harvesting systems (teams), containing harvesters equipped with accumulating harvester heads and forwarders, in first commercial thinnings were an integrated harvest of pulpwood and energy wood were performed. In the beginning the plan was to study and measure 20 sites before and after harvest. Due to storms during the summer of 2010, complete data could only be obtained from 8 of these 20 sites. Seven of these sites were privately owned and one was owned by UPM, all of the sites had been pre-commercially thinned. The mean stem density before harvest was 2578 stems per ha and the mean stem volume was 0.074 m3solid over bark.On average 1518 stems/ha was harvested. The mean tree size was 0.077 m3s of harvested stems, which corresponds to a basal area removal of 11m2/ha or biomass removal of 59 raw tonnes /ha of which 41.2 raw tonnes (raw density) was pulpwood and 17.9 raw tonnes were energy wood. The thinning quality was good, leaving 1064 stems per ha after harvest and a mean stem volume of 0.105 m3 solid over bark and a mean whole tree volume of 0.129 m3 solid over bark. The harvesters? average mean productivity was 5.1 raw tonnes per hour and on average the harvester harvested 128 stems/h and the forwarders? average productivity was 7.8 raw tonnes per hour. The average forwarding distance was 294 m. The harvesters? total time consumption was 363 hours, which gives a mean total time consumption of 14.3 h per ha and 0.23 h per ton. The forwarders total time consumption was 216.5 hours, which gave a mean total time consumption of 8.7 h per ha and 0.15 h per ton. The average costs was 1247 ?/ha for the harvesters and 758 ?/ha for the forwarders giving an average total costs per ha of 2005 ?/ha.Stem density before harvest affected the harvesters? productivity strongly and the amount of biomass harvested per ha had a clear connection to the harvesting costs (?/tonne).