Bull Hog Masticator Thins Forest

Santa Fe watershed protected by thinning trees to prevent forest fires

Staff -- Rocky Mountain Construction, 1/22/2007

It looked like a myriad of obstacles would stand in the way of reducing the density of the ponderosa pine forest of northern New Mexico's Santa Fe watershed. The list of concerns included access to the remote location some seven miles up the Santa Fe River Canyon, with the main work being done at an elevation of 7,000 feet to 10,000 feet and sometimes on extreme slopes.

The other concern was more social in nature: Canyon Road is the only access to the work site, and it also happens to pass through some of the oldest dwellings in the region. Therefore the idea of logging trucks and heavy machinery passing within just yards of adobe buildings up to 400 years old wasn't met with a great deal of enthusiasm.

A different solution needed to be found for reducing the ponderosa pine stands from a stifling 2,000 trees per acre to 60 to 100 trees per acre in the forested areas and to 20 trees per acre along the ridge lines for fuel breaks.

The work needed to be done in order to protect the city of Santa Fe's watershed. With over 40 percent of the city's water coming from this watershed, the risk of a large catastrophic fire was too great at the current ponderosa pine densities. If the forest burned it would wreak havoc on the water supply system by throwing tons of debris into the system in the form of erosion.

Given that the work area was remote, with many miles being cross-country, the option of removing the cut materials was nearly impossible. But the option of cutting, piling and burning wasn't feasible either for several reasons, including public perception.

USDA Forest Service entomologists were concerned about the cut trees' oils being slowly released into the air over a long period of time and attracting the western pine beetle, thus creating another problem.

On a different project, Bill Armstrong, a forester with the Santa Fe National Forest, asked fellow foresters and equipment suppliers if anyone had ideas for how to reduce fuel loading when a burn and/or removal wasn't feasible. He received back an invitation to observe a demonstration of what a masticator could do to a forest.

He was impressed. "You can't tell a piece of machinery has been there," said Armstrong. "You don't know what was there before they started working. There are no stumps; it is pretty amazing." Armstrong, one of the primary foresters involved on the Santa Fe project, decided that masticating the trees would be the best option for the first phase of work that needed to be done on the Santa Fe watershed.

Forest Rehab of Libby, Mont., won the contract to work on the Santa Fe watershed. "We run two excavators with Fecon heads on them," said Don Peterson, field superintendent. "I have a Fecon Bull Hog 40 on a Hitachi 225 USR with about 167 horsepower, and the other is a Fecon Bull Hog 40 on a Cat 312. We work on extremely steep slopes with our equipment. We'll work until 50-percent slope. Most of the trees are between 10 inches to 12 inches in diameter."

"The results are great," said Fran Peterson, owner of Forest Rehab. "The Fecon Bull Hog is very conducive to nutrient recycling. We didn't haul any wood out of the area because there are no roads."

Armstrong added, "The Fecon head renders the trees into a packed mulch that doesn't burn that hot. It is a compact fuel bed that the fire burns through at a very low intensity or just smolders."

If the mulch catches fire, it won't burn so intensely nor spread out as it normally would. "What we are doing is not really reducing the fuel load," explained Armstrong, "We are rendering it into a form that won't really burn that hot."

He went on: "One of the goals was to get stuff growing. By grinding that material up it provided a mulch on the ground. The end result of that was really desirable. It seemed to be a medium that really encouraged grasses and forbs to come up, and it really maintained moisture in the soil for a long time."

It is vital for the health of the watershed that grasses and forbs begin growing and filling in the forest floor, because their root structures stabilize the soil.

"The Rocky Mountain Research Station (USFS) did a study before our work that showed the erosion rate was 4 tons per acre," said Fran Peterson. "After we used the Fecon heads to do the work, the erosion rate went down to a 1/2-ton per acre. They're extremely pleased with the Fecon Bull Hog treatment, and other agencies are looking at using the Fecon for their watersheds."

The risk of attracting pine beetles was also diminished by masticating the trees. "When you masticate, it dries out a lot faster and drawing bark beetles is greatly reduced," said Deb Allen-Reid, New Mexico zone leader for forest health in Forest Service Region 3, who was happy with the quick drying time for the mulch.

"We did all of the fuel breaks with a Fecon head because the chips are different sizes and we get a very even distribution of wood chips," said Don Peterson. "We reduced the tree densities that were running about 1,000 to 2,000 per acre to the U.S. Forest Service's requirement of 20 trees per acre for the fuel breaks."

In the other areas of the forest the environmental impact statement called for tree densities to be reduced from 800 to 2,000 trees per acres to 60 to 100. Using the Fecon heads and some hand clearing on the areas difficult to reach, Forest Rehab completes about 1,000 to 1,200 acres of work in about three to four weeks.

"We work in harsh conditions, and equipment reliability is a major concern for us," said Peterson. "We haven't had to do a thing to the Fecon heads but grease them. We've had nothing ever go wrong with the Fecon head, which is really important when you're working in the remote regions of the forest."