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Partial Cutting

The Part Cuts '99 demo in BC saw a variety of equipment and methods for partial cutting. By Jim Stirling

By Jim Stirling

 

Partial cutting is a management tool that is becoming increasingly important in the forest industry. Frequently there is no choice but to practice partial or selective cutting techniques if the industry is to have access to large areas of forestlands. Partial cutting is a method of balancing timber harvesting with multiple social and environmental objectives: a meeting place for lots of needs. That's why the timing of Part Cuts '99 for three days in September was most opportune. The idea was to present some of the biological, planning and operational considerations of partial cutting and demonstrate equipment types suited to it in an outdoor workshop. The demonstration site was about 66 kilometers southeast of Vanderhoof in central British Columbia.

It was attended by about 90 people representing the federal and provincial governments, applied research and educational institutions, forestry consultants, industry operations staff and associated interested parties. Its organizers included the BC Ministry of Forests and the Vanderhoof Forest District, Forest Renewal BC, the Canadian Forest Service, the Forest Engineering Research Institute of Canada, the University of Northern BC's department of continuing education, the Northern Silviculture Committee and the forest industry. "A range of techniques and equipment are required to handle smaller wood and protect the remaining stand," explained the Part Cuts organizing committee in its preamble to the workshop. "Multiple entries also require sophisticated long term planning and a good understanding of the biological processes through to rotation and into the next rotation." During the workshop, it quickly became apparent that conventional planning and operational assumptions won't cut it in partial harvesting situations. "Our stocking standards are based on clearcut harvesting and with smaller openings those things change.

We need more information on that," said Leisbet Beaudry, a forester with Madrone Consultants Ltd. in Prince George. Beaudry talked about the changes in microclimate introduced by partial cutting and their impact on regeneration. "We also have to think about the next pass when considering regeneration," she added. Windthrow is an inherent problem when making openings in a forest stand. It results from the complex interaction between climate, site and management factors. Stephen Mitchell, an associate professor in the department of forest sciences at the University of British Columbia, recommends assembling a diagnostic framework to assess and manage windthrow. "The first step in the diagnostic framework is the preparation of a landscape-based overview map of current and salvaged windthrow," commented Mitchell. "These maps can also be used to build more quantitative models of windthrow risk." The operational aspects of partial cutting require a high numbers crunch game, reported Brian Harding from Quality Forest Consultants in Prince George. He referred to a partial cutting situation in high elevation spruce/balsam stands where retaining arboreal lichen for caribou winter range was a management objective.


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Among the harvesting equipment at work at the demo was the Farmi 9000 forwarding trailer powered by a four-wheel drive Valmet forestry-dedicated tractor designed for partial cutting and commercial thinning applications (above). The demo also included the Board Bandit portable band sawmill for in-the-field milling of logs removed in partial cutting operations

 

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He said per meter costs were about 80 per cent higher with that prescription, compared with conventional clearcut harvesting sites. But although productivity declined, the fewer stems that were harvested were larger. "We found line skidders and hand fallers were the way to go and they have to work as a team," he said. Participants in Part Cuts '99 saw demonstrations of a range of equipment options for partial cutting solutions. A Timberjack 1270B harvester working in tandem with a 1210B forwarder were the largest machines on site. However, a light footprint is a design feature of both machines, and low ground pressure equipment is a prerequisite for any sensitive partial cutting sites. The 1270 was equipped with a Timberjack 762B harvesting head for trees with 60-centimetre diameter butts.

The Timbco T445D feller buncher with 56-centimetre Quadco hot saw head brings several advantages to partial cutting applications. The machine has zero tail swing, meaning it can work from narrow trails and cause less damage to residual stems and understory. It can also work on slopes up to 55 per cent. An LKT50 line skidder was among the pieces of equipment ideal for smaller-scaled operations and woodlots. It exerts low ground pressure (five psi) from an articulated frame less than two metres wide. The machine is fitted with a double drum winch and powered by a 48kW Perkins diesel. Its average production was given as up to 30 cubic metres/day with one operator in timber 80 years old, 30 metres in height and 26-centimetre diameter at breast height. The Farmi 9000 forwarding trailer powered by a four-wheel drive Valmet forestry-dedicated tractor is designed for partial cutting and commercial thinning applications. The Farmi trailer works from a dedicated trail system.

Its onboard, telescopic loading boom can reach 6.6 metres and lift 1,100 kg at three metres. The forwarder's payload is 9,000 kg of logs up to eight metres in length stowed between three sets of movable bunks. The definitive horse power was demonstrated by Matt Jonke of Nechako Valley Horse Logging of Fort Fraser, BC. Minimal site disturbance and damage to residuals are among horse logging's plus es. The ability for single tree selection, with no piece size restriction, on trails only a metre wide make the horse useful in riparian zones or watershed restoration projects. Henry Klassen of Vanderhoof was on site to demonstrate his Board Bandit Portable Band Sawmill for in-the-field milling of logs removed in partial cutting operations.

The mill can handle 76-centimetre diameter trees, 7.3 metres long. The Board Bandit can process dry or green softwood or hardwood into beams or dimension lumber. A 4,000 board feet/day is feasible dimension lumber production for the Board Bandit. And last, but certainly not least, an important factor to consider when looking at the implications of partial cutting is the safety of all those working in the bush. "When we have new systems, we have to ask if they fit the regulations," said Dave Rowe, program manager for the WCB's prevention division in Prince George, who was attending Part Cuts '99. "One thing's for sure, we all have to learn." He added the board's prevention division was there to help companies and contractors ensure safety is integrated into any new partial cutting system.



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