Tree invasion has economic impact for grassland owners

Protecting one’s investments is economic common sense. So why do so many ranchers do so little to prevent the invasion of trees on native grassland and pastures across Kansas?

Good question, according to Doug Spencer, Marion County rangeland management specialist.

“If you want to maintain your grass at its current production rate, you have to control your trees,” Spencer said. “Ranchers really need to be aware of those trees because the more they have, the less grass production they have as well.”

Employed by the Natural Resources Conservation Service office in Marion, Spencer knows firsthand the detrimental effects overgrazing and subsequent tree invasion has on rangeland.

With grassland prices soaring as high as $1,100 per acre, Spencer said each acre stymied by unwanted trees and brush is essentially money out of the landowner’s pocket.

“It’s funny how trees affect land values, because hunters think there’s a big buck behind every tree, so treating the land almost causes land values to decrease in some case,” he said.

But Spencer also is concerned about the intrinsic value of the state’s tallgrass prairie-at least, what’s left of it.

“I hate to see another acre of it go under tree canopy,” he said.

Problem trees

Trees that provide unwanted canopy include hedge, locust, cedar and Siberian elm.

“More prevalent around here are your hedge and cedar trees, though,” Spencer said. “But it kind of depends on what seed source is local and how it got started.”

Whether the problem is miniscule or monumental is gauged by the percentage of tree canopy, Spencer said.

“Canopy percent is pretty much finding out how much shade a tree casts at noon,” he said. “Then you see how many trees are on an acre and that allows you to determine the canopy percent because that’s directly affecting the grass underneath the tree.”

Invasion impact

A tree invasion isn’t limited to one specific area of a pasture, but Spencer said the most likely spot is lowland areas because they tend to be deep in nutrient-rich soils and privy to abundant water.

Also, many lowland sites are infested with cool-season grasses that work against intense fires and tend to be heavily grazed. That’s an inviting environment for an infestation of unwanted trees and brush.

Spencer said lowland sites typically produce the most abundant forage for livestock-up to 6,000 to 8,000 pounds of air dry forage per acre. Upland sites. with moderately deep soils, might produce 3,500 to 5,000 pounds.

Equally significant, shallow upland sites can be limited to as low as 2,000 to 2,500 pounds-meaning it would take 20 to 30 acres of upland grass to supply as much forage as 10 acres of premium lowland grass.

“If the rancher can see any problem at all with trees, it’s time to react,” Spencer said. “If you wait even a couple of years, the trees can get out of hand.”

Starting and stopping

Trees seek the best ground with the least competition, such as areas that are overgrazed or where livestock tend to congregate.

Mother Nature is more than ready to assist in the importation of seeds.

“Some species of seeds are transported by birds, some by cattle and some by squirrels,” Spencer said. “Also, if you try to control a tree, it can sucker out-have shoots that come out and grow.”

For most species, controlled burning is the key to tree management.

“The nice thing about cedars is, if you can’t burn you can cut all the green growth off and they won’t grow back,” Spencer said. “So any way you can remove foliage-even if it’s with a handy pair of clippers-is very effective.”

Hedge trees can be either burned or cut down-with the stumps warranting treatment. Often, a basal bark treatment during the winter months proves effective.

“You spray up a foot or 16 inches,” Spencer said. “The advantage of (basal bark treatment) is it’s done in the winter months when farmers might have more time.”

Even when trees have been destroyed, it still takes time for the native grass to reestablish itself in the canopy area.

“We usually call it succession. The first stage is where you have weeds or something invasive come in,” Spencer said. “But over time the grass community around it will encroach back into the gap and fill it in.”

An ounce of prevention

Prevention is the best strategy against rangeland tree invasion.

“You need to identify seed sources for prevention,” Spencer said. “Identify potential for seed sources that are already in your pasture or along your fence lines.

“The other thing is to maintain and monitor your grass community,” he added. “The less opportunity or bare areas these seed sources have to invade, the better chance you have to prevent them in the first place.”

Getting started before the invasion becomes a major problem is the key to success.

“Ranchers need to identify the problem before it becomes a problem,” he said. “Don’t drive by that tree for five years and then all of a sudden it’s 10 feet tall and you think it’s too far gone.

“Get the clippers out now and spend five minutes instead of spending five hours in a couple of years.”

Battle support

Financial assistance is available to producers who qualify for it, Spencer said.

“There still are cost-share programs available for treatment under the Environmental Quality Incentives Program that focus mainly on grazing,” he said. “And for those who think wildlife is a priority, the Wildlife Habitat Incentive Program will help.”

Needs will be determined on a field-to-field basis, Spencer said.

“We’ll develop a plan of attack as far as what the producer wants to accomplish and the money available,” he said. “Once we know their concerns, we can usually fit the program to help them out.”

Spencer advises interested persons to contact him at the NRCS offices.

“Come in and see us and we’ll help you identify the weeds or trees that need addressing,” he said. “Usually, your local weed department, NRCS or the extension agent will be able to help you with treatment options.”

Spencer said information is the key to overcoming tree-invasion problems.

“A lot of producers know they have a problem, but they need to do something about it,” he said. “The more you eliminate a seed source now, the fewer problems you’re going to have later.

“A lot of times we’re in a situation where cleaning up these trees is a major act, but the maintenance is a lot less than the initial control,” he added.

“But if a seed source is close by and you don’t control that problem, chances are you’re going to face the same problem down the road sometime.”

Doug Spencer can be reached at the NRCS office in Marion, 303 Eisenhower Drive. Phone 620-382-3737 or e-mail him at

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