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Tinker’s silent land war: Invasive species battle native Oklahoma plants for dominance

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  • By John Parker
  • Staff Writer
TINKER AIR FORCE BASE - Okla. --  Just south of Tinker's Prairie Land neighborhood stands a rolling field dotted with Old World bluestem grasses, the sunny yellow flowers of black-eyed Susans and the Christmas-tree shapes of stubby Eastern red cedars.

A gravel walkway called the Scissortail Trail winds through the 30-acre prairie where Oklahoma breezes often bend the cottonwood trees and knee-high grasses.

It's a place where families enjoy nature outside their back doors and fishermen dangle lines for large-mouth bass and catfish in the Prairie and Primrose ponds. The field's abundance of water, cover and habitat attract roaming wrens, butterflies, Texas horned lizards, coyotes, grasshoppers and bobcats.

But despite all the prairie's peaceful airs, there's a silent war going on. Underneath the soil and above it, invasive and harmful non-native plants are battling indigenous plants for supremacy.

Studies have shown that when invasive species win those battles, the land's ecosystem winds up with fewer native plants and, in turn, fewer insects, birds, mammals and other wildlife. What was a thriving habitat becomes more barren.
The stakes in the Scissortail field war are high enough that even the U.S. Department of Defense joined the fight.

Last year, the DOD awarded a $2.2 million grant to researchers at Oklahoma State University and collaborators at the University of Indiana-Bloomington to study optimum ways to remove damaging invasive species from prairies and re-establish native ones.
OSU's Karen Hickman, a natural resources and ecology management professor, and Gail Wilson, a fellow scientist in OSU's Natural Resource and Ecology Management Department, are part of the three-state study.

Previous research has shown that invasive species not only crowd out native plants, they also destroy soil microbes, such as fungi and bacteria, that most native species rely on to grow, Dr. Hickman said.

Nearly all the native grass species in the Tinker field have a symbiotic relationship with fungi, said Dr. Hickman, who is also president of the Oklahoma Invasive Plant Council.

"These grasses have their roots coming down, and they have this fungus that kind of extends around them and this fungus brings minerals, nutrients and some water into the plant," she said. "Meanwhile, the plant gives the fungus carbon and energy it can't get from photosynthesis, which it doesn't do."

Invasive species like Old World bluestem grasses interfere with that process, Dr. Hickman said.

"What we found was the native plants that were growing in this Old World bluestem soil didn't have any of that relationship," she said. "There was nothing. They wouldn't grow and they can't reproduce."

One of the Scissortail field experiments is marked by small aluminum poles in the ground near the head of the trail. Researchers first grew native prairie plants in microbe- and fungi-rich soil in the greenhouse, and then planted the potted seedlings in the "war zone" near Old World bluestem at the field.

"We call them nurse plants," she said. "The goal is to see if those nurse plants can nurse back those fungi, because it is less damaging to the native prairie if we only use little pots."

Finding a way to re-establish native plants without using chemicals or other methods to destroy invaders could have a big economic and environmental impact for military and civilian land management, she said.

"Currently, you have to tear up a native prairie to be able to restore that native prairie," Dr. Hickman said. "So we had a problem with that -- an ethical dilemma. You don't want to destroy something you're trying to save."

Another part of the research involved pinning down and spacing out nearly two dozen approximately 20-by-20-foot black tarps in the field. The heat and lack of light is designed to kill off Old World bluestem in the plots.

Researchers will later put down native nurse plant seedlings, such as big bluestem and prairie coneflower, to see how they grow and affect the soil, among other approaches and controls.

John Krupovage, Tinker's natural resources manager, said the research will help the DOD in its ongoing responsibility for managing 19 million acres of U.S. land used for military bases, training ranges and more. The study has the potential to lower land maintenance and restoration costs, he said.

New methods from the study could benefit national defense by accelerating habitat restoration and regaining healthy natural systems, Mr. Krupovage said.

"Habitat loss and fragmentation causes the decline of many species of wildlife," he said. "If this happens to an appreciable degree, species may become threatened or endangered. That starts to tie our hands as far as military land use, or it could cost us much more money in the long run, and we want to stay away from that.  It behooves us to keep natural systems healthy as we build across the base."