Brush control enhances a habitat

Conservationists call the old ranch an environmental jewel and a sportsman’s paradise.

It has 11 miles of tidal front on a Gulf Coast bay. Thousands of acres of freshwater wetlands, salt marshes and native rangelands offer vital fish and wildlife habitat. It’s home to hundreds of species of birds and animals, including the endangered whooping crane. 

As good as the habitat is, it could be better, experts say. They started to work on that in 2015 with brush control.

This is Powderhorn Ranch on Matagorda Bay near Port O’Connor on the Texas Gulf Coast. In 2014, a coalition of conservation organizations pooled funds to buy the 17,351 acres, one of the largest tracts of virgin coastal prairie in the state.

Texas Parks & Wildlife Foundation (TPWF) took possession of the property with plans to donate it to the Texas Parks Wildlife Department (TPWD) for a state park and a wildlife management area. On October 1, 2018, nearly 15,000 acres of the ranch became the state’s newest wildlife management area.

While the foundation held the property, managers began improvements on the old ranch. One of the first was brush control.

A Woody Invader

The problem is running live oak, a plant related to, but not the same as, the majestic coastal live oaks on the ranch.

Running live oak is a short, scrubby cousin that invades grasslands and increases in density to create nearly impenetrable thickets.

“They say 5,800 of the 17,000 acres here are in running live oak,” says Gene McCarty, who managed the property for TPWF. He still oversees the part planned for a state park. “Grassland restoration is a very high priority.”

TPWD biologist Daniel Walker contends the running live oak shouldn’t be as dominant on the landscape as it is now. “Wildlife don’t use it much. The benefits of control far outweigh the negatives,” Walker says. “This was open grassland at one time — coastal prairie — and grassland birds are some of the most imperiled species in the world.”

The biologist explains that, before settlement, only scattered mottes of coastal live oak would have dotted the predominant prairie here. A vigorous stand of grass and wildfires would have kept the scrubby running live oak in check. With civilization, those controls disappeared.

More recently, the only things holding back the running live oak have been wet lowlands — the plant doesn’t like wet feet — and shredding by grazing lessees. But lessees only shredded roadsides, senderos and a 300-acre trap.

“They had to shred three times a year to maintain it,” McCarty says. “Cattle mainly worked the lowlands where no running live oak grew.”

 Two-Step Restoration

Fire will play a role again in maintaining the prairie, the habitat managers say. But burning only top-kills green running live oak, so it resprouts from the roots. Their plan is to root-kill the running live oak with Spike® 20P herbicide and then follow up with prescribed burns.

“We have studies of burning running live oak without a treatment of Spike,” McCarty says. “If you can get a fire to go through it, you get some temporary grass growth. But within a year, the running live oak comes back and shades out the grass. We think we can keep it at bay with fire, but we can’t get rid of it.”

The foundation aerially applied Spike 20P on 2,800 acres in December 2015 and another 1,000 acres a year later. The aircraft dropped the pelleted herbicide at the rate of 10 pounds per acre (2 pounds active ingredient). The treatments were made possible through a grant from the Coastal Bend Bays and Estuary Program and a donation from The Dow Chemical Company. McCarty expects to treat more tracts in coming years.

The herbicide is stable on the soil surface until moisture dissolves it into the soil. From there, it’s absorbed by roots and moved to the leaves to inhibit photosynthesis of susceptible woody plants.

“In the applications, we stayed away from the mottes of coastal live oak,” Walker says. “We left an untreated distance of about three times the height of the trees.”

By the autumn after the first application, the managers detected no injury to the nontarget coastal live oaks. About 90 percent of the treated running live oak appeared dead.

Native Grasses Boom

In the treated brush, native grasses were growing “in it, around it, under it and through it,” McCarty says. “Before we treated, there was no grass there.”

Walker wasn’t surprised. The seed source for tallgrass prairie is still there, he says. He expects to recover bushy bluestem, big bluestem, Indiangrass, Florida paspalum and seacoast bluestem.

The managers planned to defer grazing at least two years after application to build grass for fuel and then install a prescribed burn. They burned the first-treated area in March 2018, which cleaned up most of the dead brush. They’re planning a second burn to finish the cleanup, converting it back to grassland savanna.

Open grasslands here benefit birds, from meadowlarks and quail to shrikes and aplomado falcons, as well as mottled ducks, one of the few nonmigratory duck species.

“And the Powderhorn is important to the health of Matagorda Bay,” McCarty says. “It provides filtration for water moving across the landscape. Restoring grasslands will help that.”

The managers expect much of the property will continue to be leased for grazing. They can use rotational grazing to help manage habitat, they say.

The habitat is still here because of cattle.

 

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™®Trademarks of Dow AgroSciences, DuPont or Pioneer, and their affiliated companies or their respective owners. Always read and follow label directions. ®Spike 20P is a trademark of Nutrichem Company Limited. Contact your state pesticide regulatory agency to determine if a product is registered for sale or use in your state. Consult the label before purchase or use for full details. Always read and follow label directions.