Scientists hunt for native plants to fight incendiary invader of the West

Scientists hunt for native plants to fight incendiary invader of the West

11 August 2014

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USA — A local; late bloomer with a desire to put down deep roots. Must be comfortable with dry spells and an occasional fiery outburst. Ability to outfox strong, hot competition will be crucial.

The desired partner here is not of the human variety. For scientists with the Chicago Botanic Garden, the Bureau of Land Management and anyone else who’s contending with America’s worsening wildfire problem, the ideal match would be a plant capable of crowding out cheatgrass, one of the West’s most troublesome invasive species.

Known to ecologists as Bromus tectorum, cheatgrass is a non-native plant that has become a massive headache for land managers — Utah state Sen. Steve Urquhart once likened the plant to “a 6’8″, 250-pound, tattooed, heavily armed, escaped-from-death-row invasive species that is taking over the West.”

Most recent scientific estimates say the invasive plant has devoured more than 99 million acres in the Great Basin and Intermountain West, not only displacing native habitat but also helping to drive the significant uptick of acres burned by wildfire each year.

According to Andrea Kramer, conservation scientist with the Chicago Botanic Garden who is working to find solutions to this problem, cheatgrass thrives in spring but then dies when summer arrives.

“It leaves this really crispy, standing dead plant mass that’s just waiting for the dry season and the next lightning storm to start a fire,” Kramer said. “It’s really just kind of like a tinderbox.”

Losing battleground

Recent research found that on areas where cheatgrass is present, fires were twice as likely to burn as where native plants still thrive (ClimateWire, Dec. 5, 2012). Moreover, Kramer explained, cheatgrass is especially good at moving back in after a wildfire has scorched the land, whereas many native species have adapted to wait for more hospitable conditions before they establish themselves.

Adrienne Pilmanis, ecologist with BLM’s Colorado Plateau Native Plant Program, explained that her agency has tried multiple tactics to rid the West of cheatgrass, from grazing to mowing to chemical treatments. Scientists are even experimenting with biocontrol methods, such as fungal pathogens, to give native species a better chance of survival.

But as evidenced by cheatgrass’s continued rapid spread, no single solution to the problem has been discovered.

“It’s a challenge, we’re fighting hard,” Pilmanis said. “There’s some places where we feel like we’re winning — there’s been successes — and other places where [due to] the scale of the problem, it may take us a while and more resources to really get a handle on it.”

Among the efforts to find a natural method to deal with cheatgrass is Kramer’s Conservation and Restoration in Changing Environments Project. On a series of 20-by-20-meter plots north of Grand Junction, Colo., Kramer, her students, and her colleagues from Northwestern University and the Chicago Botanic Garden are testing different seed varieties, hoping one will emerge as a “native winner” that can thrive in a cheatgrass-dominated environment and help dampen wildfire risk.

Few plants come back as quickly from burnout

After a wildfire burns through an area that was previously seeded with cheatgrass, land managers like BLM often quickly seed the area with noninvasive plant species. But it’s been difficult to pick out what plants stand a long-term chance and will also work in harmony with the wildlife, pollinators and various human uses that existed before the fire.

To give land managers an idea of what plants might be best to incorporate into post-wildfire seed mixes, Kramer located her test plots on land burned in a wildfire in July 2012 that was previously dominated by cheatgrass. Planting took place in autumn after the researchers, in association with the federal government’s Seeds of Success collection program, collected seeds by hand from a variety of promising native species.

Kramer has returned to the site four times, twice in the spring and twice in the fall, to check on what is growing in the plots. As expected, the cheatgrass returned in full force: “We’ve confirmed that cheatgrass is a really impressive plant,” Kramer said ruefully.

But so far, researchers have also identified a handful of promising species that are also proving resilient, mostly wildflowers including the hoary tansyaster (Machaeranthera canescens) and the yellow bee plant (Cleome lutea).

These plants are more successful because they grow quickly and devote a great deal of energy to establishing roots — something cheatgrass is especially good at, meaning it often sucks water and nutrients away from other plants. They also thrive on disturbed land and grow later in summer, Kramer explained, when the cheatgrass has already died off for the year.

Potshots at a moving target

But no one solution has yet been discovered. “Over the longer term, they will help keep cheatgrass at least at bay,” Kramer said, but “none of the plants that we grow are going to be able to completely extinguish cheatgrass from the landscape.”

According to Pilmanis of BLM, while Kramer’s research is helping land managers learn what might be better to plant after wildfires in the future, it will likely take a wide variety of methods to successfully eradicate cheatgrass.

“We don’t have any silver bullet solution yet; that’s kind of an inherent problem with ecology,” Pilmanis said. “Ecology is just messy.”

Moreover, climate change is adding “a whole other layer of complexity” to the search for native winners, Kramer explained. A plant that might thrive on the Colorado Plateau today may not be able to withstand drier, hotter conditions that scientists project will occur in the Southwest’s near future, meaning the seed researchers are essentially aiming at a moving target.

They are currently testing to see how different native seeds can survive in different climates, Kramer said, hoping to identify characteristics of a plant that can hold its own against cheatgrass, wildfire and climate change.

But Kramer isn’t without hope: “It’s been exciting to see those species showing up, being able to produce seeds and showing up again the second year,” she said. “But cheatgrass is definitely a worthy competitor, so we’ll have to let this keep playing out over multiple years.”

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