“Defend the Core” — Fighting back against rangeland invaders in sagebrush country

February 24, 2022

Defending healthy cores, like this one in Oregon, is the focus of WLFW’s “Defend the Core” strategy for maintaining healthy rangelands across the West. Photo: Jeremy Roberts, Conservation Media.

NRCS’ Working Lands for Wildlife is investing in big-picture, proactive ways to keep healthy sagebrush grazing lands from becoming infested with unwanted invasive annual grasses.

By Brianna Randall

Envision driving through a western ranch with the windows down. Tall green and gold bunchgrasses wave in the wind. Wildflowers bloom between waist-high shrubs. The sunny afternoon is alive with birdsong and buzzing insects, the air clean and scented with sage. This is what we call the intact core—large chunks of healthy, thriving native rangeland.

Wildflowers on the range, like the balsam roots, lupine, and paintbrush pictured here, create healthy soils and keep water on the land. Photo: Brianna Randall

Healthy, and productive, sagebrush rangeland with abundant wildflowers and native perennial grasses are more resilient to invasive annual grasses. Photo: Brianna Randall

But as you drive farther towards the horizon, you start to notice less green and fewer flowers as the ground turns shades of brown, tan, and purple. Beneath the sagebrush, the graceful long-lived bunchgrasses are now interspersed with short, drying grasses, their seeds pricking through your socks. This transition zone is where healthy range is giving way to invasive weeds like cheatgrass, ventenata, and medusahead.

Drive even further from the core, and unpleasant invasive annual grasses have choked out most native plants. Wildlife are few and far between. These weeds reduce forage for animals, degrade ecosystem health and resilience, and fuel more frequent wildfires. Rangelands this infested are much less productive for ranchers and wildlife—and extremely difficult to restore.

Characteristic sagebrush steppe rangeland where cheatgrass has invaded and choked out most of the desirable grasses and forbs. Photo by Jaepil Cho.

Luckily, people who depend on and care about America’s valuable sagebrush lands are banding together to fight back against unwanted invaders. Through Working Lands for Wildlife (WLFW), the USDA’s Natural Resources Conservation Service (NRCS) is investing in a new, proactive strategy: First, defend the core. Second, grow the core. Third, mitigate impacts in heavily infested areas.

Flipping the script

If it sounds like battle tactics, that’s because western landowners are indeed engaged in a war on weeds, and have been for over a century. And a shift in strategy is overdue, since the status quo—reactive, piecemeal treatments once invasive annual grasses become a problem—hasn’t worked.

“In the past, we would go to the worst places first, which is like sending in an ambulance when the land is already in need of life-support,” said Jeremy Maestas, a USDA-NRCS ecologist.

Instead, WLFW is “flipping the script,” explains Maestas, to prioritize preventative care for healthy, intact places in order to keep them productive and expand them. “I think of it as providing annual checkups to keep the land thriving, instead of a last-ditch visit to the ER when it’s already a crisis.”

As invasive annual grasses take over more rangeland, they become more costly and difficult to remove.

Until recently, conservation practitioners lacked the technology to see the big picture of where the remaining intact rangelands remain, as well as where invading grasses are coming from and how fast they are infiltrating core areas. Breakthroughs in remote sensing and cloud computing have enabled scientists to produce detailed vegetation maps, along with easy-to-use tools like the Rangeland Analysis Platform (RAP). These maps and tools are finally giving landowners and resource managers the information they need about the condition of rangelands around them and empowering people to be more strategic and proactive in fighting weeds on a regional scale, rather than trying to save tiny islands.

WLFW is partnering with local, state, and federal managers to prioritize where and how to halt rangeland invaders by leveraging RAP’s vegetation data to map intact cores and see where invasives are taking hold. These maps serve as a basis for partners to develop a shared game plan for directing conservation investments.

Invasive annual grasses, like cheatgrass, are expanding across the West as shown in the graphic produced with the Rangeland Analysis Platform.

Defend the core, grow the core

Land managers have long known that it’s far more cost-effective and efficient to treat weeds early before they spread. The trick, however, is working in the right landscapes and simultaneously treating infestations on adjacent rangelands so invasive annual grasses don’t quickly re-invade.

Protecting core rangelands from cheatgrass benefits producers along with wildlife.

“These problems are contagious,” Maestas said. “You can spray cheatgrass in your backyard until the cows come home, but if all the neighboring lands around you are infested it’s an exercise in futility.”

Put more succinctly: “If there’s no seed, there’s no weed.”

In sagebrush country, the best way to keep out invading annual grasses is to prevent them from ever becoming established and to maintain a resilient, healthy native plant community that allows no room for incoming weeds.

“Job number one is to defend the cores,” Maestas said. “If we anchor our efforts here then move our way out, we’re less likely to get flanked by invasives.”

Defending cores means continually monitoring for any invasive annual grasses, and caring for native range plants through sustainable land management practices.

The next priority is to grow these cores by bolstering perennial plants and removing invasive seed sources on their periphery. In sagebrush landscapes, this often includes using herbicides to get rid of any invasive grasses and their seeds in the soil followed by re-planting native grasses, shrubs, and forbs where needed.

Finally, the strategy acknowledges the need to mitigate problems in heavily infested areas to reduce harm to human life and property. For instance, rather than trying to restore a large swath of cheatgrass back to sagebrush habitat—a costly and difficult endeavor—the emphasis should shift to protecting nearby communities from the hotter, more frequent wildfires caused by cheatgrass. Mitigation measures might include building fuel breaks, green strips, or targeted grazing to reduce the fine fuels (grasses) that spread wildfires.

Innovation and adaptation are also factors in the “Defend the Core” approach. This might include employing new, cutting-edge herbicides that reduce the seed source for several years instead of just one season. Another option is to encourage more flexible grazing practices so ranchers can put livestock in the right place at the right time to minimize the build-up of invasive annual grasses.

Hope in Action

WLFW’s “Defend the Core” approach is already being deployed in a handful of western states beleaguered by invasive grasses. Enlisting a collaborative partnership, Idaho’s Cheatgrass Challenge pioneered application of a statewide strategy to tackle invasive annual grasses. They were followed shortly thereafter by Oregon with the rollout of the SageCon Invasives Initiative. Launched in 2019 and 2021, respectively, both initiatives have already drawn in millions of dollars to help landowners reduce the threat of invasives on sagebrush rangeland. Regional partners, including the Western Governors’ Association and the Western Association of Fish and Wildlife Agencies, are helping share the “Defend the Core” recipe with other states and embed this approach in conservation strategies across sagebrush country.

WLFW is poised to help more states develop big-picture strategies to “Defend the Core”, guided by its framework for conservation action in the sagebrush biome. In addition, WLFW is investing Farm Bill conservation dollars on hundreds of ranches each year to fight back against invasive annual grasses and maintain healthy working sagebrush lands.

“This is a new, proactive path forward: save what’s intact and build out from there. It requires neighbors working together to pinpoint and protect the best rangelands left,” Maestas said. “This is how we get ahead of invasives instead of simply chasing the worst problems.”

This common strategy to protect—and grow—the best rangelands is also benefiting people and wildlife in the Great Plains, where the “Defend the Core” approach is keeping invading trees like eastern redcedar at bay. Read more here.


The Sage Grouse Initiative is a partnership-based, science-driven effort that uses voluntary incentives to proactively conserve America’s western rangelands, wildlife, and rural way of life. This initiative is part of Working Lands For Wildlife, which is led by USDA’s Natural Resources Conservation Service.