The Most Imperiled Terrestrial Ecosystem On The Planet

TALLGRASS PRAIRIE NATIONAL PRESERVE, Kansas — High along the Southwind Nature Trail, the tallgrass prairie waves in all directions, a mix of present-day reality and historical mirage stretching to the horizon much as it did more than 150 years ago.

But tall prairie grasses nodding in the breeze here at Tallgrass Prairie National Preserve in the Flint Hills and in a small number of similar landscapes reflect a tiny fraction of those once found within a 450,000-square-mile swath of North America stretching from Canada south through the Dakotas, Nebraska, Illinois, Iowa, Oklahoma, Kansas, and down to the Texas border.

Today, the vast majority of what was an estimated 140 million to 170 million acres of tallgrass prairie is gone, plowed under by 19^th century agricultural sprawl and the development that followed.   

Clinging to the remnants is a variety of species designated as threatened or endangered under the U.S. Endangered Species Act. Despite losses of countless plants and animals, these at-risk species still comprise some of the world’s highest biodiversity. This remaining fraction of their habitat is North America's most at-risk land biome, still shrinking under pressure from development, its heritage species still dwindling. It remains a window into the country’s natural heritage fading.

Beyond North America itself, prairies and other grasslands are “the most imperiled terrestrial ecosystem on the planet,” notes a 2022 University Nebraska study, but they “have relatively little federal or international protection…” While there are between 3.8 million and 4 million acres that in fact are protected as U.S. national grasslands, that’s minuscule when compared to the overall 193 million acres held within the national forest system.

Most of what’s left on the eastern edge of tallgrass landscape in Iowa and Illinois are “postage stamp prairies,” small patches interrupting massive landscapes of bean and corn fields, said Justin Meissen, who heads the Research and Restoration Program at the Tallgrass Prairie Center at the University of Northern Iowa.

Notable exceptions to the postage-stamp prairie pattern remain across the Great Plains that stretches west to the Rocky Mountains:

• The U.S. Forest Service in 1996 created the 18,226-acre Midewin National Tallgrass Prairie in Illinois that was the first tallgrass prairie national grassland.
• The USFS-managed Sheyenne National Grassland in North Dakota covers 70,000 acres, a good portion of which is tallgrass prairie.
• Homestead National Historical Park in southeastern Nebraska lays claim to 100 acres of restored tallgrass prairie.
• To the south of Nebraska, the Tallgrass Prairie National Preserve protects 11,000 acres of waving grasslands in Kansas.
• Roughly 150 miles from Tallgrass Prairie, in nearby Oklahoma the nearly 40,000-acre Joseph H. Williams Tallgrass Prairie Preserve is managed by The Nature Conservancy (TNC).
• In Canada, about 12,000 acres are protected at the Manitoba Tall Grass Prairie Preserve.

As far back as the 1930s the National Park Service mulled the idea of a grasslands national park either in South Dakota or Nebraska, though it was dropped when the United States entered World War II. In 1960, the U.S. Senate was urged by the congressional delegation from Kansas to create a Prairie National Park there, but local opposition killed the request.

“We only have about 4 percent [of the 170 million acres remaining],” Tony Capizzo explains while navigating the national preserve’s Bottomland Nature Trail on a recent hike.

That surviving prairie land still has much to offer, and it could use some help, he and other experts say.

A Human Stampede

Butterflies, bees, insects, and other invertebrates colonize and enrich the prairie by pollinating vegetation and aerating and fertilizing soils that Capizzo labels “some of the most productive farm ground in the world.”

Meissen refers to tallgrass prairie as “this nation's rainforest, both because of its wholesale destruction, but also the diversity is kind of world-class.”

“Now, the number of species is not as high as the rainforest, but if you think about species per area, [it holds] some of the highest diversity in the world,” he explained during a phone call. “Really, within one meter, within one-square meter, you could get 50 species. That’s very unique.”

It was a robust “rainforest” of grassland biodiversity, structured by big bluestem, Indiangrass, switchgrass, and other grasses that towered over purple asters, yellow sunflowers, western prairie fringed orchid, and other prairie wildflowers. Attracted into these prairie ecosystems were greater prairie-chickens, northern bobwhites, kestrels, turkeys, coyotes, snakes, cottontails, and other birds, small mammals, reptiles, amphibians, and swarms of insects and armies of spiders.

Some grassland prairies include bison, those woolly animals that create “wallows” where they’ve flopped on the ground to rub themselves. Those compacted areas hold rainwater that in turn nourishes delicate vegetation and water bugs and attracts reptiles and amphibians along with rodents and small mammals looking for a drink.

North American Relic

The Great Plains began to rise more than 65 million years ago during the Cretaceous Period when the Western Interior Seaway covered the middle of North America. Today’s rich soils in the plains got their start from the organic detritus of fish, amphibians, reptiles, seaweeds, and any land-rooted vegetation that was washed into the sea and sank to the seabed. At the same time, the uprising of the Rocky Mountains sent rivers and their sediment loads downhill into the landscape that became the Great Plains.

As the prairie evolved and diversified with vegetation — the Konza Prairie Biological Station at Kansas State University has counted more than 500 species of vascular plants in tallgrass prairie — it became a giant filtration system thanks to the deep-set root systems. Tallgrass prairie and other grasslands “mitigate drought and flood risks, filter and replenish groundwater, prevent soil erosion, and provide habitat for hundreds of plant and animal species,” notes the World Resources Institute.

But the grasslands’ beneficial attributes have been steadily vanishing since the Homestead Act, lost to contraction either due to farming, encroachment of woody vegetation, or urban sprawl.

Disappearing prairie lands have contributed to staggering losses of such grassland bird species as the chestnut-collared longspur, mountain plover, bobolinks, sage grouse, greater prairie-chicken, and Western meadowlarks. According to the 2025 State of the Birds report from the U.S. Committee of the North American Bird Conservation Initiative, birds that rely on shortgrass, tallgrass, and mixed grass prairies have declined 43 percent since 1970.

Woody encroachment drives away some birds, noted Capizzo.

“They see a vertical structure like a tree or a tower and that's a possible predator perch.,” he said. “If you give that bird that choice when she is going to make a nest, she's going to avoid 30 acres from that single tree.”

Also gone, for the most part, are bison, the largest ecosystem engineer on the continent that 200 years ago moved in herds so vast that they blanketed the prairie from horizon to horizon, grizzly bears, the Great Plains wolf, and elk. 

It’s not just the United States that has seen its grasslands fade. Globally, “[U]rbanization, industrialization coupled with commercial agriculture and afforestation are primarily responsible for global grassland loss this past century,” and “only a few” large grasslands have been spared, note the authors of The Last Continuous Grasslands On Earth: Identification And Conservation Importance, a paper produced in 2022 by the University of Nebraska’s Department of Agronomy and Horticulture.

“These intact regions are highly biodiverse areas that preserve rich traditional knowledge and cultural heritage. Yet there is no globally unified grassland conservation effort that has managed to identify these unique ecosystems and prioritize their conservation importance as anthropogenic pressures mount in the 21st century,” add the authors, Rheinhardt Scholtz and Dirac Twidwell.

In the United States, some of those relatively intact grasslands include the more than 20,000-square-mile Nebraska Sand Hills mixed grasslands — “the most intact temperate grassland region in the world,” claim Scholtz and Twidwell — and the Montana Valley and Foothill grasslands, two areas that have not been designated as federally protected reserves, and the Flint Hills tallgrass prairie, much of which is protected in the Tallgrass Prairie National Preserve and the Joseph H. Williams Tallgrass Prairie Preserve.

Nurturing The Past

At the Tallgrass Preserve’s headquarters outside Strong City, Heather Brown underscores the value of tallgrass prairie.

“The monarchs, the regal fritillary butterflies, those species need the prairie to survive,” said Brown, the preserve’s chief of interpretation. “They need butterfly milkweed; they need all the other wildflowers that are necessary for their basic survival. They feed on that. The monarch butterfly, we know that their habitat just keeps getting smaller and smaller.”

The remaining tallgrass prairie offers habitat for federally listed threatened and endangered species, such as the regal fritillary butterfly, which the U.S. Fish and Wildlife Service in 2024 proposed for listing as an endangered species due to the loss of 99 percent of its habitat, and the Topeka shiner, a federally listed endangered minnow species found in some of the national preserve’s waters.

Other threatened and endangered species that depend on tallgrass prairie include the Western and Eastern prairie fringed orchids (threatened), whooping crane (endangered), northern long-eared bat (endangered), eastern persius duskywing, a moth (endangered), leaf prairie clover (endangered), Indiana bat (endangered), and greater prairie-chickens (threatened).

Private efforts and government actions are taking some steps to conserve what’s left of the tallgrass prairie, though not on a large scale.   Rather, there are the postcard prairie patches that Meissen referred to and a handful of larger protected areas, such as the 11,000-acre Tallgrass Prairie National Preserve. A 2024 report by a handful of conservation groups did recommend including grasslands in the 30 percent of area to be protected by 2030 under the Global Biodiversity Framework adopted by nearly 200 countries in 2022.

Unfortunately, said Meissen, tallgrass prairie continues to shrink in the United States.

“In the Dakotas there's a lot of remnant tallgrass prairie that is being converted at this point. Obviously, the price of corn and beans is often the determining factor on whether we do or do not lose any more in any given year,” he said. “That tends to spur a lot of expansion into places where it didn't make any sense to try it before. … There's a huge pressure on any remnants.”

But tallgrass prairie can be restored. That’s being demonstrated on roughly 500 acres of bottomlands at the national preserve that TNC has worked with the National Park Service to restore, turning a previously farmed area into a vibrant and diverse patch of tallgrass.

“When this property originally became a unit of the National Park System, these fields between us and the creek were either in row crop or they were planted to pasture grasses,” Capizzo said. “One of our projects has been to restore native plants, native grasses, native wildflowers, and kind of recreate what this bottomland prairie community would look like.”

Along with using a commercial seed mix to revegetate the bottomland, the Park Service and TNC used hand-harvested prairie seeds from elsewhere in the preserve. The work brought upwards of 90 species of perennial wildflowers, along with switch grass, Indiangrass, and big bluestem (aka turkey foot due to its distinctive seed heads) to the Bottomland Prairie laced by the meandering Fox Creek.

During the height of the growing season, some of the grasses tower over a 6-foot individual. Among the many wildflower species is the Maximilian sunflower, a golden magnet for monarch butterflies.

“We're kind of in peak monarch migration right now,” Capizzo said last September as he paused next to waving sunflower sprays on which several butterflies had landed. “The intent when we do this prairie restoration is to capture the full range of native biological diversity and to manage it in a way to get different habitat types — shortgrass prairie, tallgrass prairie — so that we can offer habitat to all the native tallgrass prairie biological diversity.”

That diversity ‘travels,’ too, as some of the monarch butterflies tagged at the national preserve have been found in monarch preserves in Mexico, he said.

Along with hosting native species such as greater prairie-chicken and box turtles, the national preserve attracts migrating species such as sandhill cranes, grasshopper sparrows, Canada goose, pied-billed grebes, and shorebirds including snowy egrets and herring gulls.

“There's a consortium called the Western Hemisphere Shorebird Reserve Network that recognizes the Flint Hills as a landscape of hemispheric importance,” pointed out Capizzo, noting that nearly three-quarters of the country’s population of buff-breasted sandpipers, estimated to range from 35,000 to 78,000 individuals, visit the Flint Hills twice yearly on their migrations.

What’s Being Lost

The University of Northern Iowa's Meissen puts a fine point on the value of restoring tallgrass prairie.

“It's very important for us to have tallgrass prairies, at least knowing how to recreate them,” he responded. “They provide us a blueprint for soils that will grow food. And that's not going to be something that we can restore over short periods of time.”

The prairie if restored also can help slow climate change, Meissen said. When homesteaders turned over the prairie, they unleashed “an insane” amount of carbon into the atmosphere, he said.

“There's a tremendous amount of carbon under [prairie] remnants in particular, and once those are gone the cat is out of the bag,” Meissen said.

Brown turns to timely 19^th century quote from D.W. Wilder, a historian and newspaper man, when she talks about the vast loss of tallgrass prairie.

“He talks about in the 1880s that, ‘We ought to have saved a park in Kansas, 10,000 acres broad. The prairie came from the hand of God, not an inch or a foot desecrated by improvements of cultivation. It is only a memory now,’” she recited.

“And so, by the 1880s they were definitely seeing it going away, its demise."

Kurt Repanshek founded National Parks Traveler in August 2005. Since then, as its editor-in-chief, he has grown the site’s audience to more than 4.5 million a year, as well as its reputation and relevance. A veteran journalist whose 40+-year career started with The Associated Press, Repanshek has interviewed presidential candidates, members of Congress, and reported on such natural disasters as the 1988 wildfires that swept across Yellowstone National Park.

This project was made possible in part by the Park Foundation.