Prairies are endangered ecosystems in Iowa. Their remnants map their futures

This is the third installment of Nature’s Alarm, a series about endangered and threatened species and research in Iowa.

At the Corriell Nature Preserve near West Liberty, Tom Rosburg lifted a small magnifying glass to his eye and squinted at the plant fragment in his grasp.

Swaths of parched grasses surrounded him and painted the ground a burnt golden. Pops of green patches dotted the distance, signaling areas blessed with water amid the drought. The still air left the landscape frozen in time, save for the slight tremors of soft breezes disturbing the hush. The clipping in his hand — featuring tiny yellow flowers and delicate leaves — was just one part of the plant community he was trying to map.

Rosburg, an ecology and botany professor at Drake University, has been identifying plants for 30 years. His specialty? Prairies. He explores them armed with a map, sheets of paper and an expert eye at identifying plant species. This summer, he’s working at the degraded sand prairie at Corriell Nature Preserve — one of about a dozen similar projects he’s currently working on.

“People often ask me how I can identify all these plants,” he said as he tromped through vegetation. “How many people do you think you can recognize if you just see the picture of their face? Hundreds, right? … You can do it with people. I just do it with plants.”

Prairies were once the most plentiful ecosystem in Iowa. Now, just 0.1 percent of their historic range remains — a mere echo of their former glory. Of the 400-some plant species listed in Iowa as endangered, threatened and special concern, more than a quarter are prairie species.

In the face of such loss, researchers like Rosburg are giving hope to prairies' future. Studies like his serve as the foundation for preserving — and creating — more of this endangered ecosystem in Iowa.

“Over 99 percent of our prairie is gone,” Rosburg said. “The prairie that we have left is the only prairie that we have that can tell us what used to be. How did this prairie landscape once look?”

Decline of prairies

The prairies we know today started growing around 9,000 years ago in Iowa after the last glaciers melted away. Over time, they covered an estimated 23 million acres in the state. They mostly sprouted as tallgrass prairies that could surpass 5 feet in height — even up to 15 feet after a much-needed burn.

The habitats supported rich plant life: There can be as many as 30 different plant species in just a square meter of healthy prairie, including both grasses and wildflowers. They were one of the most productive ecosystems on Earth at that small scale, Rosburg said.

Bison and elk once roamed Iowa to graze on grasses. Gray wolves were never far behind, hunting for easy prey. Smaller critters — badgers, mice and foxes — lived among the grasses. Birds chased insects in the vegetation, spied prey from the skies or stopped by during migrations. Snakes slithered. Turtles burrowed. The ecosystems hummed with biodiversity.

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That biodiversity came to a halt as settlers started filling the state in the 1800s. The agriculture industry began to explode — and prairies took the brunt of the damage.

Starting in the 1850s, Iowa lost about 2 percent of its native prairie a year — totaling 3 million acres a decade, according to the Iowa DNR. Eighty years later, less than 30,000 acres of prairie remained.

Iowa’s crops owe their productivity to the very ecosystems they replaced, said John Pearson, an Iowa DNR ecologist and botanist. The plants accumulated organic matter in the soil as their extensive root systems — some burrowing more than 15 feet underground — cycled between growth and death.

“As the plants grew for hundreds and hundreds of years, they accumulated organic matter” that helps plant grow, he said. “The fact that we had so much prairie in Iowa leads directly to why we have so much fertile cropland in the state today.”

Documenting diversity

For dozens of hours, Rosburg will traverse the degraded sand prairie where livestock used to graze. The habitat still is hanging on.

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There, he scribbles down the scientific names of each plant species he spots, noting their abundance and sometimes their size. If the magnifying glass hung around his neck isn’t enough, he takes plant sample home to his microscope. If he spots a listed species, he ties a biodegradable orange flag around it.

Last year, he made almost 1,400 plant observations in the Corriell Nature Preserve sand prairie. Eighty percent of the species were native. One of them was listed as special concern in Iowa. Those findings help the Bur Oak Land Trust — the land manager — take care of the deteriorated prairie.

“I try to produce a map of what I think is the best representation of the plant communities that were here in 1800,” Rosburg said. “That helps (the Bur Oak Land Trust) figure out their goal in terms of restoration.”

Such extensive investigations into the past can reveal a wealth of knowledge about historic prairies: what species were or were not present, what their composition looked like, what soil they relied on and more.

Rosburg said he’s one of a handful of experts in Iowa that can map entire plant communities in the state. If he had to estimate, there are less than 10 such individuals left.

“I think there's a sense of, ‘Oh, well, we’ve got that all figured out,’” he said. “But before you start tinkering with things, you have to understand what you've got … You could be doing something that is drastically hurting a plant or animal.”

Such research adds to the Iowa DNR’s database of known plant populations in the state. If there are less than 40 known populations, species are candidates for the special concern status. If there are less than 20, they qualify for the threatened status. If there are less than five, they qualify for the endangered status.

But there are likely more endangered plant species than we know about. And those species could be in graver danger than we realize.

Some population counts include data that stretches back to the 1980s. That data may no longer be accurate 40 years later amid threats like land mismanagement and invasive species.

“If someone went back and looked at the populations, especially the ones before 2000, it’s questionable whether or not they're still there,” Rosburg said. “There's not a lot of follow up in that database to make sure that a record still is viable.”

A reconstructed future

The most intact prairie remnants are found today in the Loess Hills, where an estimated 90 percent of the remaining tracts are found. Several state preserves harbor a few dozen acres of remnants each. The rest are scattered across the state in small fragments that aren’t wholly protected from development, especially if they’re on private property.

The remnants are also subjected to newer stressors. Only highly managed sites still experience fire. Before settler arrival, Indigenous people likely managed prairies with prescribed burns, or lightning would naturally spark blazes. Without that fire, trees and shrubs can shade prairies to death. Invasive plants can also crowd native prairie plants and drive them out.

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“What's driving the loss of prairies shifted from being plowed up during the pioneer days to a more modern context where it’s challenging trying to keep up all the species from encroaching,” Pearson said.

Iowa can never get back the prairies now sacrificed to agricultural production. The only way to add more of the endangered ecosystem back to the landscape is through reconstructed prairies, where biologists and conservationists attempt to replicate historic prairies.

Newly restored prairies may not be as productive as their predecessors that grew for thousands of years. But their mere existence creates habitat for pollinators, plants and critters. Their roots enrich soil long depleted from agriculture. And their creation can help connect the few prairie remnants left to create larger habitats.

Recreating prairies must be done from scratch — and the few prairie remnants Iowa has left are serving as models.

“If we're trying to make prairies back out in the landscape, in my mind, it should be done in a way that helps build back what the prairie landscape once was,” Rosburg said. “We should be paying attention to what these remnants show.”

The prairie restoration movement started in the 1970s. There’s no central database for how many acres of prairie have been restored in Iowa since. But after decades of work, it’s assumed to be in the tens of thousands of acres.

Continued research — and continued conservation — of the precious prairie remnants remaining can make reconstruction efforts even more successful.

“Our oldest reconstruction is only 50 years old, instead of 5,000 years old,” Pearson said. “That's a hurdle that we can only overcome with the passage of time.”

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Brittney J. Miller is the Energy & Environment Reporter for The Gazette and a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; brittney.miller@thegazette.com