Western native plant societies urge ban on exotics

Though species such as forage kochia bring benefits, some researchers worry their growth will be out of control.

FOR THE IDAHO STATESMANSeptember 22, 2013 

Ecologist Erin Gray, studying forage kochia in southern Idaho, found it spreading beyond seeded areas.

PROVIDED BY UNIVERSITY OF MONTANA

An exotic plant with beguiling characteristics for range managers has brought a call for caution from botanists.

Forage kochia, which grows in alkaline and salty soils, provides forage for livestock and wildlife, creates effective firebreaks and competes with cheatgrass. The small shrub with a bouquet of stems and narrow, light-green leaves has been seeded on 400,000 to 700,000 acres of public rangeland around the West since 1984.

“After watching rangelands sit for year after year with nothing but cheatgrass and seeing how forage kochia can help there, it does seem to be a miracle plant in some cases,” said Blair Waldron, a research geneticist in the U.S. Department of Agriculture Forage and Range Research Laboratory in Utah.

But forage kochia evolved in the steppes of Central Asia, and a coalition of native plant societies from Montana, Idaho, Oregon, Arizona, Utah and Nevada are trying to halt its planting.

The groups sent a letter in August to the USDA encouraging the agency to stop seeding introduced species — among them forage kochia, tamarisks 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.

WON’T STAY PUT

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 be-yond some of the seeded areas.

Gray surveyed these areas for her master’s work and inventoried non-native and native species. She 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 more than two decades ago, where it is reasonable to expect native plants to move back in.

While these findings 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 remedy what Waldron calls “extremely disturbed rangelands where nothing else but cheatgrass will grow.” Forage kochia can grow where native plants “won’t establish and they won’t persist,” he said.

The hope is to bring these lands back and slow down the cheatgrass-wildfire cycle.

But the likelihood of restoring them to their original ecological state is slim, especially considering the demands of varying land management goals.

FIRE AND FOOD

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.

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 that about 50 percent of plantings fail, which might be a result of the poor land.

Plants can adapt, though.

Consider buffelgrass, an exotic bunchgrass cited in the native plants societies’ letter to the USDA. It was first planted in Mexico and the U.S. Southwest in the 1930s. For four decades it stayed put.

But then the grass jumped the fence, so to speak, and started growing in rockier soils and took off across the Sonoran Desert. The U.S. Forest Service estimates that from 1973 to 2000, buffelgrass spread from 19,000 acres to more than 350,000. By 2006, it covered more than 4 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, the species’ effectiveness and impact needs to be evaluated.

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

Retired Boise 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 overtaken 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 cheatgrass,” Rosentreter says. “But we can stop using forage kochia before it’s out of control.”

Mills’ story was provided by the University of Montana School of Journalism.

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