This research quantified volume losses during the felling and conversion of pine sawtimber trees, and determined the utilisable timber left infield.The title of the article is “Fibre volume losses of eight softwood clearfell harvesting systems in South Africa”, and it appeared in Southern Forests: a Journal of Forest Science, 2012, 74(2), pp 133 to 149. The authors were P Ackerman and R Pulkki. The different types of volume losses investigated were high stumps, felling and crosscut saw kerf, log allowances, excessive removal of merchantable wood, incorrect log trimming allocation and utilisable wood left infield. Different aspects compared included merchandising at roadside landing and merchandising yards, motor-manual or mechanised felling, and tree size. Systems consisted of felling with chainsaws or drive-to-tree feller bunchers, extraction was with cable or grapple skidders, and all crosscutting was done with chainsaws.
The results showed that total wood utilisation across all systems was 92%. Stumps were 7 cm (2.8 in) higher than specification, which translated into a volume loss of 0.79% for mechanical felling and 0.07% for motor-manual felling. Saw kerf losses from mechanised felling was 0.92%, which was considerably higher than the 0.15% of motor-manual felling. Excessive trimming of logs and tops not being extracted resulted in large losses of 2.02% and 2.57% respectively. These volume losses translated into an additional annual harvested volume of 421,722 m3. Motor-manual felling systems caused greater losses than mechanised felling systems for most of the volume loss classes. Please access the journal for a full account of the research. Source: http://www.tandfonline.com/doi/abs/10.2989/20702620.2012.701412