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Harvesting Short-Rotation Hardwoods

Since 1997 PF Olsen in Northland has been involved in establishing, managing and harvesting Acacia mearnsii (black wattle) and Acacia dealbata (silver wattle) on behalf of a Japanese-owned NZ-based company, NZ Plantation Forest Company Ltd. The purpose of their investment in the growing of this short rotation hardwood is to reduce the harvesting pressure on naturally grown tropical hardwood forests such as you find in the Amazon Basin. The product is harvested, taken to the Portland chip mill just south of Whangarei, chipped and exported out of Marsden Point to Japan where it is used in the production of high quality paper.

Acacia logs harvested and transported to the Portland chip mill awaiting drum debarking, chipping and shipping to Japan for the production of high quality paper.

The harvesting of this forest crop with piece-sizes <0.15 m3 is very challenging, and it became clear that a new approach was needed to harvesting the trees efficiently and to prevent a cost blow-out. That new approach includes a high degree of mechanisation. PF Olsen is working with an innovative company called Fibre Resources Ltd which is experimenting with different machine configurations to improve efficiency. Whilst there is still some way to go to find the optimum configuration, the following is showing promising results:

Felling head: A 28 tonne Timbco feller/processor equipped with a 22 inch Waratah fells and bunches the acacia on the cut-over.

Processing: A 22 tonne Caterpillar excavator with a Logmax 750 processing head debarks the trees and cuts them to length in the cut-over and lays them in bunches.

Extraction: A Timberjack 660D grapple skidder extracts the processed and bunched logs and carries them to the skid off the ground to minimise mud contamination.

Loading: A 22 tonne Daewoo excavator with a pulp grapple loads the trucks which take the logs to Portland for chipping.

Initially trucking was done using conventional open-bolstered logging trucks. Due to the large number of pieces in each load, trials are being undertaken with self-loading bin trucks.

Current trials involve using self-loading bin trucks to transport logs to the log yard as opposed to the conventional logging trucks. With such a large number of logs in each load you can see the advantage of a high-sided bin truck over a conventional logging truck.