Study finds one-time herbicide use decreased native plants, may have increased invasive plants

September 23, 2009
Matt Rinella, shown here with his pet llamas, recently published an article in the journal Ecological Applications showing that it may not always pay for ranchers to use herbicides to kill invasive plants on rangelands.

( -- Matt Rinella, faculty in Animal and Range Science at Montana State University and an ecologist at the Fort Keogh Agricultural Experiment Station in Miles City, recently published the results of a 16-year study in the journal Ecological Applications.

Rinella and his colleagues found that, due to an application of the herbicide Tordon made 16 years prior, native wildflowers--including Missouri goldenrod and yarrow--had been reduced to precipitously low levels and the target invasive weed (leafy spurge) had potentially increased. Although the herbicide dissipated after a few years, the plant community was permanently altered.

"There is some evidence that some of the native forbs went locally extinct," said Rinella.

When herbicide wasn't used, many native forbs did similarly well in grazed and non-grazed plots. Plots that were sprayed and grazed fared better than plots that were sprayed but not grazed. Cattle grazing can benefit native forbs because cattle prefer eating grass to forbs. Additionally, cattle trample the soil, loosening it for seeds that are inadvertently sown by cows. However, Missouri goldenrod and yarrow did not recover, regardless of grazing.

"The critical question was, 'Which was worse for native biota, invaders or things done to control invaders?'" asked Rinella.

Rinella's study was a continuation of a research project started by one of his graduate committee members, Bruce Maxwell, now faculty in land resource and environmental science at MSU.

"A study like this can tell us a lot about the long-term target and non-target effects of herbicides, so it's nice that Matt could keep working on this project," Maxwell said.

Maxwell studied the effectiveness of herbicide use in controlling leafy sprurge, an invasive plant, as part of his graduate research from 1982-1984. He made observations after 10,000 acres were sprayed--minus several areas covered with tarps--at the N-Bar Ranch near Grass Range, Mont. Fences kept cattle out of some of the sprayed plots and some of the non-sprayed plots, creating a mosaic of plots that were sprayed and grazed, sprayed and not grazed, not sprayed and grazed, and not sprayed and not grazed.

Sixteen years later Rinella, then a graduate student of Maxwell's, visited the N-Bar ranch with Maxwell, other students and faculty. The exclosures were still standing, presenting an opportunity to study how a one-time aerial spraying of herbicide and more than a decade of grazing affected the rangeland.

"Our cautionary tale is told using herbicide-treated grassland, but our results should be considered wherever invasive species management damages native species," said Rinella.

Provided by Montana State University (news : web)

Explore further: Invasive Species Alter Habitat to Their Benefit

Related Stories

Invasive Species Alter Habitat to Their Benefit

August 9, 2006

When scientists study habitats that alien species have invaded, they usually find predictable patterns. The diversity of native species declines, and changes occur in natural processes such as nutrient cycling, wildfire frequency ...

Invasive grass may impede forest regeneration

April 9, 2007

The nonnative invasive grass Microstegium vimineum may hinder the regeneration of woody species in southern forests. Chris and Sonja Oswalt (Forest Service Southern Research Station) and Wayne Clatterbuck (University of Tennessee) ...

Biodiversity passes the taste test and is healthier too

January 14, 2009

Cattle and sheep grazed on natural grasslands help maintain biodiversity and produce tastier, healthier meat, according to a study funded by the Economic and Social Research Council (ESRC). The research, part of the Rural ...

Biodiversity passes the taste test and is healthier too

January 30, 2009

( -- Cattle and sheep grazed on natural grasslands help maintain biodiversity and produce tastier, healthier meat, according to a study by the University of Exeter. The research concludes that pasture-based farming ...

Recommended for you

Study suggests fish can experience 'emotional fever'

November 25, 2015

(—A small team of researchers from the U.K. and Spain has found via lab study that at least one type of fish is capable of experiencing 'emotional fever,' which suggests it may qualify as a sentient being. In their ...

How cells in the developing ear 'practice' hearing

November 25, 2015

Before the fluid of the middle ear drains and sound waves penetrate for the first time, the inner ear cells of newborn rodents practice for their big debut. Researchers at Johns Hopkins report they have figured out the molecular ...

How cells 'climb' to build fruit fly tracheas

November 25, 2015

Fruit fly windpipes are much more like human blood vessels than the entryway to human lungs. To create that intricate network, fly embryonic cells must sprout "fingers" and crawl into place. Now researchers at The Johns Hopkins ...


Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.