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Lady Bird Johnson Wildflower Center Utilizes Fire to Selectively Control Invasives in Native Prairies

Posted on: Monday, 8 August 2005, 12:00 CDT

A cooperative project between the U.S. Fish and Wildlife Service, National Park Service, Texas Cooperative Extension, Robert J., Jr. and Helen Kleberg Foundation, and The Lady Bird Johnson Wildflower Center has determined that summer fires can control invasive, non-native, King Ranch bluestem grass without eradicating native vegetation. This finding is important because it allows selective control of the spread of this species in locations where it is problematic.

King Ranch bluestem (Bothriochloa ischaemum) is currently listed as an invasive, terrestrial plant species by the Union of Concerned Scientists. It is native to Asia and Central Europe and has become widespread throughout the southern part of the United States of America since its introduction in the early 1900's. Although, some ranchers find King Ranch bluestem useful for cattle grazing, elsewhere it is considered to be a problematic invader of fields and roadsides in north central, central, and southern Texas, crowding out native plants, threatening rare native plant species, and even suppressing small animal diversity.

Serving as project leader, the Wildflower Center tested various management treatments, including mowing, prescribed burning, herbicide use, and seed sowing, at the U.S. Fish and Wildlife's San Marcos National Fish Hatchery and Technology Center in San Marcos, Texas. The same management treatments were tested at the Lyndon B. Johnson National Historical Park in Johnson City, Texas. The study was conducted from January 2004 to May 2005. Additional testing and analysis will continue through June 2006.

"Mowing, controlled prescribed burning, herbicide use, and seed sowing, are all management treatments that are readily available to land owners," said Wildflower Center Ecologist Dr. Mark Simmons. "This suite of treatments was tested in two different ecosystems in an effort to uncover an understanding of the interaction of treatments and the biology of this species."

Although the timing is essential, controlled seasonal fire performed as well as herbicide treatments. Initial findings demonstrate that while King Ranch bluestem is suppressed by summer fire, many native grasses and wildflowers are not. Winter fires were found to spur growth of King Ranch bluestem. "Therefore, timely installation of summer, or growing season, prescribed fire offers a less expensive alternative to other control methods, helping land managers selectively control the spread of this species, while sustaining more desirable grasses," said Simmons.

"These are important findings for land managers who have problems with King Ranch bluestem in the Edwards Plateau and Blackland Prairies," said Dr. Allen Rasmussen of the College of Agriculture and Human Sciences at Texas A&M University - Kingsville. "This study shows there are effective alternatives to help maintain our native grasslands. I'd like to see this work expanded into other areas, such as South Texas, to refine the timing of the burns to meet land objectives."

According to the U.S. General Land Office's 1999 fiscal year report, $70.7 million in federal funding is allocated for controlling invasive plant species. In 2000, BioScience, a publication of the American Institute of Biological Sciences, reported that the economic impact of invasive plants is $13 billion per year in the United States.

The Wildflower Center's additional invasive projects include:

-- A roadside re-vegetation study funded by the Federal Highway Administration

-- The Invaders program, an innovative campaign whereby volunteer "citizen scientists" are trained using a specially developed Invasive Species Early Detection and Reporting Kit

-- The "Pulling Together" initiative, www.texasinvasives.org

-- Hosting Texas' first statewide conference on non-native invasive plant species, November 17-19, 2005, www.texasinvasives.org

Source: Business Wire

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