Speaker
Description
Boom-corridor thinning (BCT) has been proposed as a promising alternative for treatment of dense stands with small-diameter trees, as it promote higher harvester productivity due to effective crane work in comparison to traditional selective thinning (ST). BCT can be performed using high to low degree of systematic approach, from strict (following a strict pattern) to flexible (adjusting the pattern to e.g. stand structures). BCT could also be combined with selective thinning of un-thinned zones in-between boom-corridors (BCTcombo), but which has yet not been studied. The objective was therefore study and compare harvester productivity in BCTcombo and ST in young dense first thinning stands.
The study was performed in North Karelia, Finland in two-storied birch stands. Time studies were executed in 18 study units, to which treatments (BCTcombo and ST) were randomly assigned. The stands were of 8-11 m in height with a mean stem density of 9877 stems/ha (range 2450-16100) of which, on average, 1806 stems/ha (20%) were > 6cm DBH and 80% were below 6 cm DBH, classified as undergrowth. The instructions for the operator were to perform quality thinning and target ca 1500 future crop trees. The harvester used was a Komatsu 901 featured with a 11 m crane and a multi-tree handling harvester head. The trees were harvested at full length or bucked into sections (i.e. tree parts) and bunched along the strip-roads.
Based on the harvester computer data, the harvesting removal for treatment BCTcombo was on average 65 m3/ha and 3333 stems/ha, which was 18% and 13% higher, respectively, compared to ST. The average tree size cut was however 20.5 dm for both treatments. The observed harvester productivity was on average 8.5 m3/PMh for BCTcombo, which was 14% higher compared to ST. Preliminary results from this study aligns well with previous research, showing that that BCT facilitate higher harvester efficiency.
| Keywords | biomass; productivity; small-trees; tree-parts |
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