An Ontario logging contractor has proven conclusively to himself, his sawmill and the provincial government that mechanical harvesting causes less damage to residual trees than hand felling, both in shelter wood and selective harvesting applications.

Calvin Forest Products, headquartered in Mattawa, about 170 kilometres east of Sudbury, recently switched from using as many has 12 hand-felling gangs to a Tigercat 845 feller buncher with a Koehring 22" saw head. The company has also switched from cable skidding to grapple skidding.

The result was surprising, even to Calvin Forest Products supervisor Kent Perry, who had experience with mechanical harvesting in northern Ontario. "We realized a 20 to 25 per-cent improvement in the harvesting process over the damage we had before," he says. "I was surprised that it was that good. I expected the damage to be equal to hand felling - not that much less."

Calvin Forest Products harvests a variety of softwood and hardwood species in cutblocks near North Bay. Tembec owns the harvesting rights, and each cutblock has a different harvesting prescription. In other words, residual wood may vary from cutblock to cutblock, depending on what the permit holder and the Ontario Ministry of Natural Resources (MNR) want to preserve.

Calvin Forest Products is owned by Chris Walley. He has three brothers plus his father working for him as contractors. They harvest about 80,000 cubic metres annually. Up until two years ago, they used traditional cut and skid gangs.

"In the area we cut, it's primarily shelter wood and selection harvesting," says Perry. "So, the onus was alwavs on hand felling as the best way to achieve that without having damage to residuals." The question of what is acceptable damage is a judgment call, says Perry However, as a general rule, anv bark damage on surrounding trees is considered damage. "They (Tembec) don't like to see anything over 15 per cent," he says. "That would be considered unacceptable."

At first, both Tembec and MNR were leery of mechanical harvesting. However, after seeing Calvin Forest Products' comparison of mechanical harvesting to hand felling, they now want other contractors to switch to mechanical harvesting.

While the permit holder and the Ministry were reluctant, Perry says Calvin Forest Products were promoting the idea for two reasons. Firstly, they wanted to increase their annual cut, and secondly, quality hand-felling gangs were getting more and more difficult to find. "If you wanted to cut more volume, you had to have more crews," says Perry. "That was always the game."

Finally, two years ago, they took the plunge into mechanical harvesting, intent on proving that it was at least as accurate as hand felling. Four months after purchasing their Tigercat 845, they purchased a John Deere 790 delimber with a Rogers head for roadside delimbing. Later, they added a Risley Limmit delimber, on a Cat 320 excavator. They also purchased a grapple skidder to replace their cable skidding method.

Since switching to mechanical harvesting, they have doubled production, and nearly tripled it in some circumstances. "We were looking at efficiency versus productivity - that was an important factor, says Perry. "But probably the key was to prove we could do it with minimal damage, or the same amount as with hand felling. The results were staggering."

Calvin Forest Products' study comparing mechanical harvesting to hand felling lasted approximately six months, from September 1996 to March 1997. Both Tembec and MNR could not believe the excellent results achieved. Every person who walked the cutblocks after mechanical harvesting and skidding believed the area had been harvested by hand felling "because it was so good, and they had never seen it that good. They were awed to find out it was done by machine."

The skidding process aside, there was a 30 per-cent reduction in residual damage from the cutting and felling process. "If we were running 65 to 70 per cent crown and residual damage from the hand-felling process, now we run between 90 to 95 per cent with no damage," says Perry.

The reasons arc twofold. The mechanical feller buncher can directionally fell the tree within a foot or two of where it is needed. Hand felling is not as precise. The harvester can hang onto the tree ]onger and start it falling on an exact path. Plus, the operator of the mechanical harvester can manipulate the machine's head to avoid contact with standing trees in very close proximity.

Perry's company has found that with a well-trained operator, cable skidding will do as little damage as mechanical grapple skidding. "But the skidding process benefits from the harvester's superior directional felling abilities. "We found that the skidding was better because the trees were placed better by the harvester," says Perry. "You don't get trees that have fallen where they're not supposed to fall. Tembec finds that there is less ground disturbance because the skidders don't have to churn the ground up as much, and they stay on the same trails that the harvester lays out."

Because of reduced ground disturbance, Calvin Forest Products is allowed to work longer in the spring, and Perry says their first experience with an extended spring harvest was worthwhile. They still keep one or two gangs working with the mechanical harvester. But Perry says the harvester has increased productivity substantially with less effort, and created a safer work environment.

It takes a skilled equipment operator to achieve their production and quality targets. Perry says operators familiar with clearcut mechanical harvesting often have difficulty adapting to these more demanding harvesting conditions.

"It's a long leaming curve for the operators," says Perry. "For the operator, 50 per cent of it is knowing how to operate the machine, and 50 per cent is knowing how to lay the wood down."