Research Results - Tree optimisation - man versus machine!

Can a harvester head optimise a tree as well as it can be done manually?

The title of the study was “Pinus saw timber tree optimisation in South Africa: a comparison of mechanised tree optimisation (harvester/processor) versus current manual methods”. It was authored by John Eggers, Andrew McEwan and Beatrice Conradie of the Nelson Mandela Metropolitan University, in the Southern Forests Journal (SF 2010, 72(1): 23-30). The study was carried out in both Pinus patula and Pinus elliottii.

The study was initiated due to the perceived inability of the harvester head to optimise a tree as well as the predominant manual scaling method used, specifically when the logs produced are high value saw timber logs of multiple specifications and lengths. Value and fibre recovery were investigated.

The research covered three study sites and investigated the effects of tree diameter, branch characteristics and defects such as forked trees on the manual and mechanical optimisation methods. The tree was first optimised manually (without cross-cutting/bucking taking place) and then it was optimised by the harvester head.

The results found no statistical difference between the manual and mechanical optimisation methods, regardless of tree volume, diameter, branch characteristics, stem forks and broken trees. Length accuracy with the harvester heads was also shown to be very accurate. The results apply to both value and fibre recovery.

Please access the Southern Forests for a detailed and more complete account of the research.


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