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The Log - Issue five- Research activity: FiberPlus: the impact of harvesting a small-dimension volume-recovery product

image of pile of logsBy Damian Walsh

CRC for Forestry researchers Damian Walsh and John Weidemann have been spending time in the pine forests around Tumut (NSW) lately. It has been a bit of a homecoming for Damian, having spent five years of his career working in Tumut, and a change of scenery for John to be working in pines instead of blue gums.

The CRC researchers were invited to undertake the study by our industry partner Forests NSW to investigate the productivity impact on a typical mature clearfall radiata pine harvest operation of incorporating a secondary biomass product, known as ‘FibrePlus’.

Aims of the project

Typical log products cut in the mature clearfall operations in the Buccleuch Plantation north-east of Tumut include sawlogs (6.1, 5.5, 4.9 and 3.7 metre lengths) and pulpwood (3.7–6.1 metre variable length). The sawlogs are mainly destined for the Carter Holt Harvey (CHH) sawmill in Tumut, while the pulpwood goes to the Visy pulp mill, just to the west of Tumut. Forests NSW staff wanted to know whether bringing short waste log pieces to the roadside for chipping was viable when integrated with existing harvesting operations.

image of Fibreplus chipsThese waste pieces (1.0–3.7 metres in length with a small-end diameter outside bark (SEDOB) > 4 centimeters) are created as a byproduct during normal cut-to-length processing, and are known as ‘FibrePlus’. FibrePlus would be sold either as an additional fibre source for the Visy pulp mill or as boiler fuel for Visy’s electricity cogeneration power plant.

The key was to determine the impact such a change might have on the productivity of the harvesting operation, both in the harvesting/processing phase and the extraction/forwarding phase.

Sites and studies

The CRC researchers worked with Forests NSW staff at Tumut to establish two 100-tree plots and three 2-hectare sites in a 34-year-old radiata pine plantation (1976 age class) that had been thinned twice. Forests NSW inventory crews used ATLAS Cruiser methodology to inventory every tree in each 100-tree plot. The objective was to harvest and extract one plot and one site incorporating the proposed FibrePlus product (‘FibrePlus’ plot and site) and harvest and extract the second plot and site as normal (‘control’ plot and site).

Each plot and two of the three sites were harvested using a cut-to-length two-machine system, using a Timbco 475 harvester fitted with a Rosin 997 harvesting head and a modified Timbco 820 clambunk forwarder. The third site was to be harvested using a three-machine whole-tree-harvesting system for comparison. The third site is yet to be completed.

CRC staff worked with the harvest contractor, Paul Rosin, and his crew to complete a detailed time and motion study on each plot and record the products cut and their dimensions using the harvester’s DASA4 optimising computer. Less-complex instantaneous observation studies were conducted on the harvesting of the two 2-hectare sites. A detailed time and motion study was also completed for the forwarding phase on each plot and each 2-hectare site. All products were segregated at roadside and tracked across customer weighbridges to determine exact yields from each plot and site.

Early indications suggest FibrePlus a winner

The data collected is still being analysed, but early indications are that the addition of the extra product has little—and perhaps a positive—impact on the productivity of the harvesting phase and a noticeable but not unreasonably negative impact on the productivity of the forwarding phase. The plantation proved exceptionally productive, yielding 450–500 GMt/ha of product, of which 90% was sawlog, 6% pulpwood and 4% FibrePlus.The 4% FibrePlus (approximately 20 GMt/ha) was left on site in the control plot and site.

In the FibrePlus plot and site, where the FibrePlus product was brought to roadside and chipped, the resulting chip contained approximately 3% bark and was potentially of sufficient quality to be mixed with normal roundwood chip and used for papermaking, instead of being used for boiler fuel (the last resort). In addition, the plot and site where the FibrePlus product was extracted was left without any large woody debris which will make site preparation for the next rotation easier and cheaper.

This ability to turn what was once waste into a useful product could potentially be a win-win-win situation for everyone in the log supply chain in a tight fibre-constrained market: the forest owner, the mill and the contractor.

Further potential of the data

The data collected in Tumut also has the potential to provide valuable information not only on the productivity and costs of mature clearfall operations in radiata pine (which will be incorporated in ALPACA – the Australian Logging Productivity and Cost Appraisal model), but also (hopefully) good information on how harvesting and extraction productivity varies with tree size or by product, and the effect of log length, the number of products and/or log sorts and distance on the productivity of harvesting and forwarding.

For more information, contact Damian Walsh.