Saving the Core of the Sagebrush Sea, the American West’s Largest Landscape

Sagebrush — the silver-haired, blue-green-gray shrub that gives the ecosystem its name — grows across nearly 200 million acres in 13 western states. Dry but not quite desert, sagebrush country mixes several shrub species with a dizzying array of wildflowers and bunchgrasses, flanking the lower slopes of snowy mountains and filling the basins between. It is the largest contiguous landscape in the United States, the connective tissue between forests and rivers through which people, bison, elk and mule deer have moved for ages.

Sagebrush in Craters of the Moon National Preserve. Bureau of Land Management / Bob Wick.

Indigenous peoples have made their homes in sagebrush lands since time immemorial, and dozens of its plants remain important to tribes for food and materials. The deep-rooted bunchgrasses, as livestock forage, drew colonial settlers and helped give rise to cities such as Boise, Reno and Salt Lake City. Sagebrush lands store carbon and water, regulate stream flow and support pollinators, and they are critical habitat for more than 350 species of plants and animals, among them the greater sage-grouse, pronghorn, the tiny pygmy rabbit and many songbirds.

An ecosystem in crisis

Human development has cut the sagebrush biome to half its historic range, making it one of North America’s most imperiled landscapes. Farmland, energy production and cities press in on all sides, and what remains faces an accelerating cycle of weed invasion, wildfire and drought. The intact core of the ecosystem now covers only about 13% of the biome, mostly in remote parts of Idaho, Montana, Nevada, Oregon and Wyoming. Since the parks cannot save every acre, the Park Service and its partners, helped by the Bipartisan Infrastructure Law and the Inflation Reduction Act, are concentrating on protecting and growing core habitat where it survives.

Greater sage-grouse at City of Rocks National Reserve. NPS / Wallace Keck.

Climate: not the same everywhere

Dryland ecosystems are vulnerable to climate change, but models give some reason for optimism: many core sagebrush areas look relatively stable and may be sustainable for at least several decades. The exceptions are the drier southern parts of the biome and its northeastern edge along the short-grass prairie. In parks such as Theodore Roosevelt National Park in North Dakota and Lake Mead National Recreation Area in Nevada, managers face accepting climate-driven losses of sagebrush rather than resisting them. Elsewhere — Craters of the Moon in Idaho, Grand Teton in Wyoming, the Gunnison Basin of central Colorado — direct climate effects are smaller, and the effort goes into defending the “sagebrush sea.”

Cheatgrass and fire

Fire has always been part of sagebrush country, but the arrival of cheatgrass, a non-native annual, has created a destructive loop: fire opens ground for cheatgrass, and cheatgrass feeds more fire. Climate extremes make it worse — a cool, wet spring makes cheatgrass thrive, and when extreme heat and drought follow, it dries into fuel that carries fire rapidly through the sagebrush. Many scientists agree that saving the biome depends on breaking this cycle.

A field of steppe (a type of sagebrush landscape with fewer trees and more native grasses), one year after the 2021 Trail Creek Fire in Big Hole National Battlefield. It shows remarkable weed-free resilience. Image credit: NPS.

Elevation matters. At Big Hole National Battlefield, mountain sagebrush steppe above 6,000 feet has shown impressive resistance to fire and invasion. Lower down it is a different story: frequent fires in the Clarno Unit of John Day Fossil Beds National Monument, which rises to only 2,400 feet, have severely altered its sagebrush.

The same Clarno site in 1987 (top) and in 2012 (bottom), after repeated wildfires. NPS.

Mapping the best of what’s left

Saving everything is impossible, so scientists built the Sagebrush Conservation Design: maps made from satellite images, at a resolution of 30 by 30 meters, that show where sagebrush and perennial grasses dominate, where annual grasses and conifers have taken over, and where people have altered the land. From them come core areas to defend and growth-opportunity areas to expand — and places where losses must be accepted. The strategy’s coordinator has said the maps give a sobering sense of how narrowly the effort must focus, since there is nowhere near enough money or capacity to defend all the core, but that it can succeed in more than a few places with focus and commitment.

Core and growth-opportunity sagebrush around 2000 (red), today (blue) and projected for mid-century (green) under business-as-usual emissions. NPS.

The design has become a rallying point for scientists and land managers, and the Department of the Interior has used it to direct federal infrastructure investments. More than 95% of all mapped core and growth-opportunity areas lie in just 10 parks and 10 wildlife refuges — “our best bets,” in the words of Bill Sparklin, an invasive-plant specialist with the U.S. Fish and Wildlife Service.

Defending the core at Craters of the Moon

The 700,000-acre Craters of the Moon, on the edge of Idaho’s Snake River Plain, holds more core and growth-opportunity land than the other nine top parks combined. Its lower reaches are overrun with cheatgrass, but its higher northern parts, around 6,000 feet, hold thousands of acres of intact sagebrush steppe — much of it on kipukas, islands of older ground surrounded by lava from eruptions about 2,500 years ago, which act as natural firebreaks.

Vegetated kipukas at Craters of the Moon. NPS.

The maps showed that a highway cuts through the park’s core, exposing it to fires started by malfunctioning vehicles — several recently, including one while the article was being written. Mowing and herbicide are creating roadside fuel breaks that “starve” fires of cheatgrass before they reach the sagebrush and give firefighters defensible lines, while scientists map fuel loads and simulate fire risk to show where such work pays off. Superintendent Wade Vagias calls it smart business but wants monitoring to prove a return on the investment: in a park this big, he warns, it is too easy to get carried away on weed problems that are frankly unwinnable. The Park Service’s Inventory and Monitoring Division will track the results.

Seeding the understory

Healthy native bunchgrasses and wildflowers beneath the sagebrush help it resist weeds and recover from fire. City of Rocks is removing juniper that has shaded them out. Researchers are collecting native seed and growing native plants to put in right after disturbances such as juniper removal or herbicide treatment, before weeds claim the bare ground, and partners such as Oregon State University–Cascades are rapidly expanding the supply. Some are trying to move hardier, drought-tolerant bunchgrasses upslope, and Craters of the Moon, City of Rocks and Great Basin National Park joined an experiment testing whether bunchgrass seed coated in activated charcoal survives when planted during herbicide treatment of cheatgrass. Katie Vinzant, the Park Service restoration biologist leading its part in the National Seed Strategy, puts it plainly: “We will have to get into the game at some point.”

Lessons for every sagebrush park

More than 70 Park Service units lie in the sagebrush biome. Only about 10 are slated for major conservation investment, but dozens face the same problems — and all of them stand to gain from the shared investments and lessons now spreading across the biome.

Sources

Based on Rodhouse TJ, Lonneker J, Spaak J, "Saving the Heart of the American West’s Largest Landscape," Park Science 38(1), Summer 2024, National Park Service; a work of the United States government in the public domain, with a remark by the sagebrush conservation strategy’s coordinator rewritten in hubnx’s own words. The source also calls sagebrush one-third of the lower 48 states, which its own figure of nearly 200 million acres does not support, so that claim is left out. Pictures an earlier version of this page left out were restored on 2026-09-26.