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Fire helps put grass back in grassland

Fire has been a part of the prairie landscape for centuries, but virtually disappeared after more than a century of settlement. The U.S. Forestry Service is trying to reverse that trend at the Black Kettle National Grassland in western Oklahoma with a prescribed burn program that is slowly reverting the landscape back to its natural state.

“Once we began to build settlements, people didn’t want fire near these settlements, and it was suppressed, which allowed for the encroachment of red cedar,” says Chuck Milner, a rangeland management specialist at the grassland. “One of the things we are interested in doing is restoring fire to the ecosystem on some sort of a natural level.”

Key Points

Prescribed burns emulate natural prairie fires, which control invader species.

Quick green-up after fire provides an excellent regrowth of quality forage.

Wildlife responds quickly to burns, which provide improved diversity.

The loss of fire in the landscape has had devastating impacts on the prairie, including loss of wildlife habitat and the encroachment of invasive species, especially mesquite and red cedar. Mesquite isn’t a serious threat to parts of western Oklahoma, including the grassland, but red cedar has made great strides in stealing the landscape from native species in the absence of fire, which kept the tree in check.

“We believe red cedar was a natural part of this ecosystem, but we also believe it lived in draws and canyons, and fire was the primary form of suppression,” Milner says. “One hundred years of [fire] suppression allowed for the encroachment of red cedar.”

Several methods are used for red cedar control, including cutting and grinding, but fire is the most effective force. An initial fire can remove smaller trees, including thousands of seedlings in each acre that are virtually impossible to see in the grassland. The smaller trees are reduced to mere skeletons after the first couple of burns, which can be eliminated with subsequent fires.

Turning up the heat

For larger trees, raising the temperature under the tree is effective in killing them if the initial fire is too small. The season plays an important role, especially in grassland moisture content.

“It has to do with raising the temperature of the cambium through a slow back burn in the winter or a fire in the summer,” Milner says. “The moisture control of the green plant in summer makes it safer, and the higher temperature makes it easier to kill the tree.”

Grazing management is directly affected by the prescribed burns, providing a flash of fresh grass growth in the wake of the fire. The cattle ranchers have not always been receptive to the fires, but once they saw the increase in forage quality after each burn, they slowly grew to accept the practice.

Cattle can take advantage of the new forages almost immediately because there is a very short turnaround before the grass is renewed and peeking above the surface.

“From a rancher standpoint, fire’s a great tool; it’ll open up more ground for grazing,” says John Pickens, a forestry technician at the grassland. “It’s absolutely amazing how fast we have a green-up; we have a green-up in a week.”

Cattle aren’t the only ones that have benefited from the newly opened landscape and fresh forage. Native wildlife is thriving in the grassland, much of which may be inclined to leave the area due to red cedar encroachment. Also, sportsmen are returning along with wildlife.

“All of it seeks to improve the wildlife, and there is a net gain in every area, especially wildlife,” Milner says. “Typically, what we’ve seen is wild turkeys like to return before the fire’s out, and every native species has returned.”

Although the grassland has 15 years in the burn program, it is a slow process, one researchers are still learning today. They know the landscape burned naturally every three to 10 years, but climatic factors, weather conditions and human habitation all have had their effects on the program. But portions of the grassland have already been returned to a prairie landscape, and the ultimate goal is to do the same for the remaining area.

“The southern Great Plains evolved with fire, and the history of this land was created with fire, but we only have a 15-year history with prescribed fire, and we’ve only scratched the surface on what we know about it,” Milner says.

Brazil writes from Carnegie, Okla.


CEDAR INVASION: Chuck Milner, rangeland management specialist at the Black Kettle National Grassland in western Oklahoma, points out cedar encroachment on what was once an area of solely mixed prairie grasses before settlers took wildfires out of the equation.

This article published in the April, 2012 edition of THE FARMER-STOCKMAN.

All rights reserved. Copyright Farm Progress Cos. 2012.