New options being explored in fight against cedar trees

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October 3, 2011 - 7:00pm

For decades, farmers and ranchers in Nebraska planted eastern red cedar trees in wind rows to prevent soil erosion. In the past 20 years, that good idea has evolved into a problem: the trees grow quickly and take up too much grazing and hunting land.

Ranchers "knew it was a problem, but nobody knew what to do about it," said to Doug Whisenhunt, grazing specialist with the federal Natural Resources Conservation Service. On a recent tour of the rugged Loess Canyons, south of North Platte, he pointed out areas where dense congregations of cedar trees made formerly lush pastures uninviting for grazing cattle.

Courtesy photo

A controlled fire burns pasture-overtaking cedar trees.


Click the image to view the Nebraska College of Technical Agriculture's 2008 Biomass Feasibility Study


Click the image to read a study titled, "From the Dust Bowl to the Green Glacier: Human Activity and Environmental Change in Great Plains Grasslands."

Collage by Dave Smith,
Nebraska College of Technical Agriculture

A collection of photos showing the growth of cedar trees in a controlled area from 1999 to 2010.

"It's nothing but solid trees, and underneath those trees -- and you can get out and take a look -- you can see there is nothing growing under those trees," he said, gesturing out his pick-up's dusty window. "You have to fight your way through it. You can't ride a horse through it. They can't find their cows in this stuff."

Some researchers specializing in the rangeland ecosystems refer to the spread of uncontrolled cedar trees across the Great Plains as "the green glacier." Research papers published on the topic reveal that over the past 20 years, their spread parallels a drop in the acres available for livestock grazing and fewer ground-dwelling birds, like prairie chickens.

(Click here and zoom in for an aerial view of the dense cedar population taking root in the canyons in Frontier County, Neb.)

A small scale experiment conducted by a faculty member at the Nebraska College for Technical Agriculture provides anecdotal evidence of how quickly cedars can take over.

Starting in 1999, Dave Smith marked off and photographed a 20- by-20-foot area of grassland just off the campus. The yearly photos he compiled make up a PowerPoint presentation he uses to illustration what he calls "a tremendous problem."

The first photo shows a small, ankle-high bushy, green cedar. The progression of photos show it growing a steady one foot every year. Making a circle around the base of the tree in the photo with his finger, Smith explained that "not only do we have height, but we have width where (initially) it wasn't affecting the grass very much. Now we have a 10-foot radius where there is almost no grass underneath it."

Smith also had students plant small marker flags where each new seedling sprouts. He was startled by the amount of germinating seeds: "Now there are 71 flags in that same plot, plus the four large trees. There is a dramatic increase in the number of seedlings."

Even though all seedlings do not grow up to become trees, ten years after Smith began his project, four good-sized trees fill the small patch he monitors, blocking out nearly all the grass that would have been suitable for grazing.

There are a number of solutions being used to clear out the cedars.

"My first choice would be to not have them there in the first place," said a chuckling Alan Mortenson. For more than a century, his family has maintained cattle along the rugged country of the Loess Canyons.

Mortenson uses a combination of mechanical means like chainsaws, bulldozers and trailers to haul them out, as well as controlled burns.

"It's just like weeding your garden," he said. "You need to look forward and know you are going to do this again in three years, and maybe five years, to try to stay ahead of it."

In the Loess Canyons area, groups of neighbors banded together to coordinate controlled burns of hundreds of acres at a time. They chopped down some of the trees, pulled the limbs under standing green trees and waited for the dead wood to dry out enough to provide good fuel.

Some burns will scorch hundreds of acres at a time.

"It's by far the most cost-effective way to control cedar tree encroachment," said Scott Stout, a rancher who serves as a fire boss on controlled burns in the area. "It's just amazing what so little input can do to your ground. For one thing you can actually see your cows to get them out of your pasture. You get your new grass, better grass."

His neighbor, Harris Grunden, said he has been "fortunate" with the fires he's used for cedar control on his land, estimating, "We've probably killed 75 to 85 percent of our standing trees. It's good for it."

Ranchers more and more often conduct controlled burns of their pastures. Now, another form of burning, inside a specialized boiler, is being advocated at the Nebraska College of Technical Agriculture.

In September, the college received a new 19,000-pound bio-mass boiler, partly funded by a set of grants. College President Weldon Sleight recently gave a tour. It's like any other boiler which converts boiling water into steam heat. The advantage is this unit will replace much of the natural gas currently used with chopped-up cedar trees. In southwest Nebraska, cedar chips are a readily available fuel.

The college will pay $40 a ton for the material. Some ranchers in the area are already considering the benefits of selling off something that's considered a nuisance. Landowner Allan Mortenson calls the arrangement "another tool for us" in their fight against the trees.

"If they can do it and save energy at the same time, it's got to be a good thing."

The engineering consultant hired by the college estimates that if the experimental project works, the cedar fuel would reduce their fuel bill by $50,000 per year.

While nearly everyone hopes the bio-mass boiler project succeeds, some ranchers are skeptical it can maintain a steady stream of cedar tree fuel.

"In theory, it looks great," said Stout, who lives north of the campus. Having cleared plenty of acres of cedar by hand, he notes that "there is a lot of variance about what they say they can do and what will actually happen. The possibility of being able of getting that crop out of the pasture and into the plant is an iffy situation."

Removing the trees is both time-consuming and costly. The price the college is paying may not cover the expense, leaving the controlled burns as a more economical method.

On the other hand, the fact that a skeptic like Stout called the cedars "a crop" could be a small victory for Sleight, who has high hopes for his bio-mass boiler project in Curtis. It'll take about 1000 tons of cedar chips a year to keep that furnace running.



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