Formed by the retreat of glaciers and deposition of loess soil ten thousands years ago.
Further formed over thousands of years by the growth and death of prairie vegetation. When grazed or burned, prairie plants shed their roots, adding organic matter and building rich, dark soil.
The appearance of the country is gay and beautiful, being clothed in grass, foliage and flowers. -Lt. Albert Miller Lea, 1835
In the mid 1800's settlers began clearing prairie for agriculture.
This process accelerated since John Deere invented the steel plow in 1837. It required less men and less oxen to operate, and could more easily slice the deep, thick roots of prairie plants.
This legacy we still live today. According to 2010 land use statistics, 95.4% of Iowa's surface area is farmed or developed. Only a combined 3.3% is in Conservation/Wetland Reserve Programs or federally owned (the other 1.3% is water).
Where there is corn, there was prairie. Where there are cities, there was prairie. Where there are counties, where there are towns, there was prairie. -Opening words of the Prairie Learning Center documentary (after a confusing scene where a child has a staredown with a stuffed lion).
Restoration The Neal Smith National Wildlife Refuge was created by an act of congress in 1990 (Neal Smith was its main proponent). The purpose of the act was to "re-create 8,600 acres of tallgrass prairie and oak savanna," making it the first refuge established mainly for the goal of ecosystem restoration.
Education is a major objective at the NSNWR. It's a major field trip destination for schools of nearby Des Moines. The Prairie Learning Center is packed with interactive displays, well-researched interpretive signs, movie screens and lab rooms. It also houses a nursery and seedbank.
Other restoration efforts include:
Seeding – Sometimes abandoned land will revert to prairie on its own, drawing from its relict seed bank. But if the seed bank has been depleted, either from a century of plowing or being out-bred by invasives, then collection, storage and sowing may be necessary.
Invasives removal – One of NSNWR's greatest struggles is removing invasive plant species, especially aggressive growers that out-compete natives and reduce biodiversity. They employ many methods. Staff sometimes cut and spray stumps with an herbicide known as Garlon. Thinner plants can be mowed. Larger trees must be girdled, or sliced around their circumference deep enough to sever their cambium. The most common yet laborious method is pulling by hand. Luckily volunteers come by the busload, as many as 150 on one occasion according to Mr. De Bruin.
Prescribed burns – Fire is another tool for removing invasive species, as well as for preventing encroachment by woody, non-prairie species. Fire is also a catalyst for regeneration, removing old growth and encouraging new. For these reasons, fire is a major component of prairie health and composition. In fact, disturbance by fire literally defines the prairie ecosystem (as opposed to a “meadow,” which is shaped by floods, droughts or other disturbances).