Thursday, September 12, 2013

Western native plant societies urge USDA to ban exotics

Posted By on Thu, Sep 12, 2013 at 3:00 PM

Forage kochia is a small shrub, a bouquet of stems with narrow, light-green leaves. It appears unremarkable, belying its utility. Forage kochia grows in alkaline and salty soils, provides forage for livestock and wildlife, creates effective firebreaks and competes with cheat grass. Its usefulness explains why it’s been seeded on between 400,000 and 700,000 acres of public rangelands around the West since 1984.

Researcher Erin Gray studying forage kochia in southern Idaho
  • Researcher Erin Gray studying forage kochia in southern Idaho

“After watching rangelands sit for year after year with nothing but cheat grass and seeing how forage kochia can help there, it does seem to be a miracle plant in some cases,” says Blair Waldron, a research geneticist in the USDA Forage and Range Research Laboratory in Utah.

But forage kochia is an exotic species, one that evolved in the steppes of Central Asia, and a coalition of native plant societies from around the West, lead by Montana’s, are trying to halt its planting.

In early August, native plant societies in Montana, Idaho, Oregon, Arizona, Utah, and Nevada sent a letter (PDF) to the USDA encouraging the agency to stop seeding introduced species, such as forage kochia and Canada bluegrass, and use native plants instead.

The introductions of these plants “were made with good intent,” the letter states. “However, we are concerned with the introduction of exotic plants, many of which have had an adverse effect on native biological diversity.”

Agencies must justify the use of non-native species based on certain requirements: They should not spread beyond seeded areas nor adversely affect native plant diversity. In the case of forage kochia, a study published in March in Rangeland Ecology and Management suggests the shrub may fall short on both counts.

Ecologists Erin Gray of the Institute of Applied Ecology and Patricia Muir of Oregon State University examined forage kochia stands in southern Idaho and found that the shrub spread beyond some of the seeded areas. Gray says the proclaimed benefits of forage kochia “could confer a competitive advantage with native plants.”

Gray surveyed these areas for her master’s work and inventoried non-native and native species. Gray found that forage kochia spread into adjacent communities whether dominated by native species or not, and that native species were sparse in sites that had been seeded over two decades ago, where it is reasonable to expect native plants to move back in. While these findings published in the paper are not definitive, they could mean that forage kochia is competitive with native plants

That’s an issue if the long-term land management goal is to restore native plant communities. The short-term goal of forage kochia is to remediate what Waldron calls “extremely disturbed rangelands where nothing else but cheat grass will grow.” Forage kochia can grow where native plants “won’t establish and they won’t persist,” he says.

The hope is to bring these lands back from the brink of aggressive monocultures and slow down the cheat grass-wildfire cycle. But the likelihood of restoring them to their original ecological state is slim, especially considering the demands of varying land management goals.

True to its name, forage kochia is not only used as a fire-resilient plant, but as a source of protein for livestock and wildlife in the fall and winter. Though public lands plantings can be roughly estimated, the extent of the shrub’s presence on private land is unknown. Agency seed specialists and seed companies estimate that about half of forage kochia seed purchases are by private landowners.

One reason cited for forage kochia’s widespread use is that its seeds, though prolific, have short viability and tend not to grow when buried deeper than a quarter-inch. Generally, establishment rates are low; Waldron says about 50 percent of plantings fail, which may be a result of the poor land conditions.

Plants can adapt, though. Consider buffelgrass, an exotic bunchgrass named in the native plants societies’ letter to the USDA. It was first planted in Mexico and the southwestern U.S. during the 1930s. For four decades it stayed put. But then the grass jumped fence, so to speak, and started growing in rockier soils and took off across the Sonoran Desert. The U.S. Forest Service estimates that between 1973 and 2000 buffelgrass spread from 19,000 acres to more than 350,000. By 2006, it had covered more than four million acres, greatly increasing the Sonoran Desert’s fire fuel load.

Tom Manaco, an ecologist in the USDA’s Forage and Range Lab, understands the outcry over the spread of buffelgrass, but he also points out that it helped stabilize the soil and prevent erosion.

Manaco says these purposeful but unpredictable introductions are the “proverbial Band-Aid,” a short-term fix in need of longer-term perspective. At some point, he says, there needs to be evaluation of the species’ effectiveness and impact.

“Do we take off the Band-Aid and heal the wound, or did the Band-Aid do its job?” he says.

Retired Boise-based BLM botanist Roger Rosentreter thinks the Band-Aid needs to go, but says it’s “hard to get the genie back in the bottle.” Once a supporter of forage kochia, Rosentreter changed his mind after more than 35 years in the field watching the degradation of arid landscapes.

He walked the desert playas where forage kochia had taken over slickspot peppergrass, listed as a sensitive species in Idaho. When Rosentreter suspected forage kochia wasn’t staying confined in certain areas, he directed researchers Gray and Muir to some of them.

“We can’t take back cheat grass,” Rosentreter says. “But we can stop using forage kochia before it’s out of control.”

This reporting was supported by Science Source, a project of the University of Montana School of Journalism.

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