You can't plant a prairie
Note: This article is a sidebar to this issue's feature story, "The Greening of the Plains."
Once the sod has been busted, prairie restoration becomes extremely difficult, to say the least. "I always say that you can’t plant a prairie," says Jim Stubbendieck, a grasslands ecologist and the director of the Center for Great Plains Studies at the University of Nebraska. "A prairie’s got to evolve over hundreds of thousands of years."
Nevertheless, many prairie advocates across the Great Plains, including Stubbendieck himself, have been trying to figure out how to plant a prairie.
Most notably, in 1990, Congress established the Neal Smith National Wildlife Refuge near Des Moines, Iowa, as an 8,600-acre experiment in tallgrass prairie re-creation — a prairie laboratory and museum. Pauline Drobney, a biologist at the refuge, says scientists there have had to learn how the prairie functions, sometimes one insect or flower at a time. After more than a decade, the refuge is functioning well. But, she says, "It took 150 years to destroy native prairie; it’s going to take at least that amount to time to put it back."
As interest has grown, and as more native prairie is lost, the frontier of restoration has moved west. In recent years, the U.S. Fish and Wildlife Service, The Nature Conservancy, and some local groups have undertaken restoration on a small scale on the Western mixed-grass and shortgrass prairie.
Mike Rabenberg, a Fish and Wildlife Service biologist in northeastern Montana, says his agency tries to plant as many as 10 or 12 species of native plants in its restoration work. That is far less than what actually grows on unplowed mixed-grass prairie; a single acre can contain 50 species of plants.
The Nature Conservancy’s Brian Martin, who has worked on several prairie-restoration projects in Montana, says mixed-grass prairie is especially difficult to duplicate, because it’s more like a quilt than a blanket. "Whereas, in tallgrass you’ll often find 100 to 300 (plant) species in a single acre, mixed-grass prairie is not as diverse in every acre," he says. Instead, each patch may have a different soil type or a slight variation in runoff that changes the suite of grasses, forbs and sedges.
"Sometimes we just have to take a shotgun approach" in planting seeds, Martin says. "We’ll plant a bunch of grasses over a broad area, and hopefully, the species will sort of sort themselves out."
The native seeds have to contend with invasive weeds and the lack of moisture in many areas. And the whole process depends on the supply of native seeds, which are very expensive, and sometimes unavailable (HCN, 5/12/03: Planting time). Sometimes, seeds must be collected by hand; Rabenberg has also been experimenting with a seed-stripper pulled behind an ATV.
At Scotts Bluff National Monument in the Nebraska panhandle, park officials are restoring prairie on the site of the former Scotts Bluff Country Club. Robert Manasek, a resource management specialist at the monument, says he and his team had to survey the region, looking for the best native prairie as a model. They removed the foundations of golf course buildings and the asphalt golf cart paths, re-contoured the land, sprayed the course with herbicide, and pulled diseased Siberian elms from the fairways. Then they had to experiment with planting methods.
They ordered seeds from Colorado because it was less expensive than collecting seeds themselves, Manasek says, even though "the best thing we could have done would have been to pick seeds from inside the park," because local strains are the best adapted to any site. No commercial dealer sold seeds for threadleaf sedge, an important plant they wanted in their mix. So a University of Nebraska group raised sedge plugs in a greenhouse. Since the initial plantings, the monument has conducted two prescribed burns on the land, trying to duplicate natural wildfire’s effects. It will be decades before the results there are known.
Ultimately, it cost more than $125,000, donated by the Nebraska Environmental Trust Fund, to restore the 42 acres of former golf course. That’s almost $3,000 per acre, far more than it costs to buy and preserve existing prairie.