Ben Dolbeare identifies a plant at Sand Prairie Scrub Oak State Nature Preserve. Chris Young/The State Journal-Register
Visit a different prairie
SPRINGFIELD STATE JOURNAL-REGISTER
Like the shifting sand, the definition of prairie changes from one location to the next.
Where the soil is rich, black and deep, towering grasses like big bluestem punctuate the landscape. In drier climates to the west or on step hillsides in central Illinois, prairie grasses and flowers grow much shorter, reflecting the lack of moisture.
In much of Mason County, the soil is sandy. Water flowing out from melting glaciers left huge deposits of sand. The soil drains quickly and the dry conditions keep the organic matter from building up in the soil.
But in this harsh environment, a special aggregation of prairie plants somehow persists.
There is prickly pear cactus — found even in roadside ditches in Mason County. One can find sand milkweed, with its interesting wavy leaves. Venus looking glass, spiderwort, porcupine grass, goats rue, hoary puccoon and the tiny yellow flowers of dwarf dandelion combine in pastel shades of green, purple, pink and yellow.
Botanist Ben Dolbeare of the Illinois Department of Natural Resources has a special affinity for the tiny dwarf dandelion.
“If you are here at the right time of the season, you will see it in flower all over,” he says. “Here, it’s common. I just think it’s a pretty plant, a real neat plant.”
Dolbeare has been developing an interest in the rare sand prairies of central Illinois recently, and he wants to share what he has learned with others.
“Very few people even know they exist,” Dolbeare says. “So, I’ve decided to do an open house.”
He’s hosting a tour of Sand Prairie Scrub Oak State Nature Preserve just outside Kilbourne starting at 10 a.m. June 20. The preserve is at the corner of 900 N. and 1500 E. just northeast of town.
The 1,460-acre preserve is a mixture of sand forest, savanna and prairie openings. Many of the trees in and around the prairie are fairly short, almost shrublike.
“We will have a walk-through with a discussion of the plants and animals we encounter,” he says.
Dolbeare coordinates the DNR’s invasive plant species program, working with a variety of landowners and businesses in the nursery trade to help slow the spread of non-native plants that can be detrimental to natural areas.
He also spent a chunk of his career studying aquatic plants, so one might think Dolbeare is out of his element in an exceptionally dry environment.
But even the tiniest plants draw his attention. Some have similar cousins, and it takes a good field guide and some patience to sort them out by species, something Dolbeare doesn’t seem to mind as he kneels down and pages through his book.
Bill McClain is a retired DNR biologist who has studied Illinois sand prairies extensively with retired botany professor John Ebinger of Eastern Illinois University.
“Visiting a sand prairie is like taking a trip into the West,” McClain says. “You are walking into an area that you wouldn’t think would be present in Illinois. It is so much different.”
In places where the vegetation has disappeared due to some disturbance or tillage, the sand can be clearly visible.
“You will find dunes of actively moving sand and plants that you truly wouldn’t expect to find — like prickly pear cactus,” he says. “In that regard, you think you are stepping out of Illinois.”
Even sandy areas are distinct. McClain says plants and animals vary from one location to the next. McClain and Ebinger have surveyed sand prairies growing on sand deposits along the Mississippi, Illinois, Kankakee and Green rivers.
“And they have been little explored, from both the botanical standpoint and zoological standpoint, and you never know what you are going to find,” he says.
Dolbeare used to teach a field biology class at Lincoln Land Community College and often brought his students to the sand prairie so they could gain an appreciation for the rare habitat.
He says he will conduct the tour in much the same way, offering some guidance at first but allowing people time to discover things on their own.
“I didn’t do a lot of deep, technical stuff,” he says. “I just wanted to expose them — help them gain an appreciation.
Dolbeare says a lot of his students had little experience outside.
“Most of my students had never been off the sidewalk,” he says.
Dolbeare says reading about ecological and biological concepts is great. But there is no substitute for one simple directive: “Go, look and see.”
To get to Sand Prairie Scrub Oak State Nature Preserve, take Illinois 97 through Petersburg to Kilbourne (about 10 miles before Havana). Past Kilbourne, look for County Road 900 N. Turn left 5.5 miles to 1500 E. The preserve sign will be on the left.
The dirt on soil
That one can find anything growing in the sand is difficult to comprehend.
In Mason County, farmers use giant center pivot irrigation systems that march in a circle spraying water to keep the sandy soil moist enough to support agriculture.
The additional moisture may help the soil build organic matter — or at least replace what is lost to tillage — said Bill Teater, a soil scientist with the Natural Resources Conservation Service.
About 30 percent of a prairie plant’s roots, for example, die back each year to contribute to building organic matter.
“But the more you till it, the more you degrade the organic matter,” Teator says. “Exposure to sun and air bleaches and oxidizes it, causing it to break down.”
In sandy areas, sand grain size helps determine whether or not organic matter will be built up in the soil or lost.
More water can be held between the grains of sand if the sand grains are small. A little more water available for plants can be the difference between soil supporting a thin stand of grass, only cactus, or just a bare sandy surface.
Soils that have more vigorous plant growth produce more plant residue, which means more organic matter builds up in the soil along with a darker surface.
Illinois’ famous “black soils” are built in loess, a fine, talcum powder-like silt that was ground up by glaciers and spread by wind. Where the loess is deep, prairie plants and their roots combined to create soil that is deep and especially productive — some of the best corn and soybean producing ground in the world.
Coarse sand is at one end of the soil spectrum and fine clay is at the other in their ability to hold water.
Teater says the silty and clayey soils that developed in flat or depressed areas can hold some of the richest concentrations of organic matter.
“It is the high concentration of organic matter that gives the soil its black color,” he says. “These dark black soils are a blessing from God. They provide a rich environment for growing crops.”
Below, a clutch of lark sparrow eggs is nestled into a cup-shaped nest. Chris Young/The State Journal-Register