SULA – In the world of heavy-duty gardening, Dyrk Krueger pulls a mighty plow.

From his seat in a huge backhoe, Krueger will spend much of the summer tending an overgrown plantation of ponderosa pine trees high in the Swift Creek drainage east of Sula.

You have to look closely to notice, but all the trees here grow in rows like corn, planted on man-made terraces that have revegetated since they were bulldozed back in 1967.

“We don’t always get to work around home anymore,” the owner of Enhanced Forest Management Inc. in Ravalli County said.

But the Swift Creek project is unusual in many ways. For one, Krueger and his employees and subcontractors are managed by the Rocky Mountain Elk Foundation, which is handling the project for the U.S. Forest Service. For another, Krueger’s job is to essentially obliterate trees and rip up soil in the service of landscape improvement.

It all goes back to the 1960s, when Forest Service silviculturists decided to terrace 13,000 acres of the Bitterroot National Forest as a way to improve tree production. The idea was that by scraping off competing vegetation, the pine trees would grow better. And the terraces would catch and hold more snow – in a place where water is the hardest-to-find resource.

The plan worked, sort of. The mechanically planted trees are a uniform 18 to 20 inches in diameter, compared to unassisted stands where pines of the same age are just 8 to 10 inches thick. And 97 percent of those planted survived to maturity.

But the great start screwed things up down the road, according to Sula District Ranger Ruth Wooding. Cutting the terraces compacted the soil, making it difficult for anything but noxious weeds to grow on the hillsides. The great survival rate meant the forest became overcrowded. But logging would have compacted the ground even more, exceeding Forest Service soil-damage standards.

So the trees grew into fire hazards prone to beetle infestations on hillsides that failed to provide much other forage for wildlife. Enter the Rocky Mountain Elk Foundation.

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RMEF stewardship services coordinator Bob Schrenk is always looking for places to improve habitat for elk and other wildlife. The Forest Service had landscape that needed maintenance, but couldn’t be simply logged or wood-chipped. And there were federal stimulus dollars available to put local people to work. By setting up a stewardship project where the outcome is research instead of wood products, all those dots could be connected.

The Swift Creek drainage has a resident elk herd of about 150 to 250 animals. But it’s winter range for another 1,000 or so elk that migrate out of the Big Hole Valley to the east.

“The big issue here is forage,” Schrenk said. “By doing this kind of work, we increase the quantity and quality of forage.”

This kind of work brings us back to Krueger and his backhoe. It’s equipped with a two-part device. One part is a “masticator” that does to mature trees what the garbage disposal in your sink does to carrots. Krueger tops a tree about 20 feet up, and then literally vaporizes the remaining trunk, blasting sawdust and pitch hundreds of feet downwind.

As he goes down, he whacks the trunk into bigger and bigger chunks. The result is a strategic mess of woody debris ranging from splinters to firewood. Too much little stuff and the soil would be robbed of nitrogen as microorganisms in the ground try to digest all the new wood fiber.

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Now comes the second part of the machine.

When the tree’s gone, Krueger plunges the attached “grapple rig sub-soiler” 20 inches into the ground. The thing looks like a cross between a John Deere plow and a sailboat’s keel. His backhoe knifes through the ground, leaving a furrow only a few inches wide.

But underneath, the sub-soiler makes a huge difference, according to Forest Service soil scientist Cole Mayn. The winged tooth at its tip de-compacts the dirt without causing too much damage to existing plants.

To prove it, Mayn takes an 18-inch planting shovel and stabs it into some untreated ground. After jumping on it, he buries about 6 inches of blade.

Then he pokes the shovel into the swath where Krueger has plowed. It sinks right to the shaft, as if he just stabbed a bag of peat moss.

“It’s basically a piece of farm equipment we’ve been able to modify,” Mayn said of Krueger’s plow. “When it goes through, you can see the wave it makes a couple feet ahead and alongside the head. We could decompact the soil with a ripper shank, but that makes too much disturbance. With this, we can feel if we’re hitting rocks or roots and move elsewhere instead of digging them up.”

A lot more research will go into this 130-acre project to see how well the land reacts to the thinning and plowing. It may need more fertilizer to attract the wildlife RMEF wants to see. It may benefit from some prescribed burning, or a different spacing of remaining trees. If a good formula can be worked out, the process may be repeated on much of the remaining 13,000 acres of terraced plantation forests in the Bitterroot National Forest.

“This is an amazing piece of history we’re standing on here,” Wooding said. “We can’t just leave these stands.”

Reporter Rob Chaney can be reached at 523-5382 or at rchaney@missoulian.com.

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