What Is a Tallgrass Prairie?
I have come to love the color and majestic stature of big bluestem. I delight in letting my open fingers run through the grass as I walk through head-high stands in autumn, until my shirt is tinted and spattered golden yellow by its pollen. If there is a king of American grasses, big bluestem must surely be it. Big bluestem is a warm-season grass, doing most of its growth during the hot summer months and finally bursting into blossom in September. By October it is beginning to shed its seed crop. Its generic Latin name, Andropogon, translates as “man’s beard,” a fine description of its flowering head.
If big bluestem is the king of prairie grasses, Indiangrass, a companion tallgrass species, would be an appropriate queen. The bronzy fall color of Indiangrass is even more beautiful than big bluestem. Its bushy head of autumn florets seems to me to resemble a golden-tasseled wand. Indiangrass and big bluestem can grow to six or more feet high in good years, and even to eight feet or more in very moist years.
Little bluestem is Nebraska’s “shaggy” prairie grass, of which Willa Cather wrote lovingly in My Ántonia. Little bluestem’s English name refers to a bluish cast on the lower leaves and stem nodes. However, by midsummer much of the entire visible plant is starting to turn a rich reddish tint. By fall one can easily recognize little bluestem by its bunch-like, shaggy shape and its wonderful overall coppery red color, almost matching the colors of an autumnal prairie sunset.
Like big bluestem, it is a warm-season species, growing the most in the summer months and sending out graceful, feathery flowering stalks in early fall. Its abundant seeds are soon dropped, but the upright stems and leaves persist over the winter. In good years little bluestem may produce two hundred or more pounds of seeds per acre, providing important fall and winter food for small mammals and native birds.
Little bluestem is easily the most important plant of Nebraska’s mixed-grass prairie. It not only vies with big bluestem for dominance in the eastern tallgrass prairie but also penetrates the entire Sandhills region. Buffalo grass was the food for immense herds of bison that once migrated through Nebraska each spring and fall. Buffalo grass is the classic short grass of western and northwestern Nebraska. It forms a mat-like turf at the ground, beginning its growth in late spring and continuing throughout the summer. To a greater degree than any of the other short grasses, it tolerates repeated grazing and is tough enough to withstand a variety of soil and climatic conditions.
Buffalo grass is unusual in that the sexes are on separate plants. Unlike the other prairie grasses, its seeds are a hard bur. Without treatment, such as chilling, soaking, or passing through the digestive tract of an herbivore, few of these seeds will germinate. This trait may have helped buffalo grass spread with the migrating bison from its geographic origins in Mexico north throughout western North America.
Although buffalo grass now occurs only in western Nebraska under natural conditions, it probably extended farther east during the drought years of the 1930s. Some cultivated varieties can grow well as far east as Lincoln, at least during drier summers.
At the center of Nebraska is the vast Sandhills region, where moist meadows and marshlands fed by water from the Ogallala Aquifer bring this region’s plant diversity to more than four hundred species, but the most important upland Sandhills plants are perennial bunchgrasses. These include little bluestem, hairy grama, and Junegrass, which all grow to heights of two to three feet. The region also hosts tall grasses, such as sand dropseed, sandreed and sand bluestem, a sand-adapted relative of big bluestem, our king of prairie grasses.
To visit any prairie in Nebraska is, in a sense, to visit with our very distant relatives, each of which has its own story to tell, if we will only try to understand. Although each season is different, autumn is a very special time to visit a Nebraska prairie. Life has by then come full circle, and it is a perfect time to sit or lie down in the grass, to enjoy the sights, sounds, and smells of nature close at hand, and to at least briefly merge one’s soul with our natural world.
When I was very young, I used to walk along railroad track right-of-ways near my home in the Red River Valley of eastern North Dakota. I didn’t know that the “turkey-foot grass” that grew higher than my head was something special and that under its more formal name of big bluestem it is a charter member of the tallgrass prairie that once covered much of eastern North Dakota. Somewhat later my mother began to teach me about some of the native prairie flowers that grew in low meadows near their once-homesteaded farm near the Sheyenne River. Today this area has been preserved as part of the Sheyenne National Grassland, the largest federally owned area of tallgrass prairie in America. I learned there to identify such beautiful plants as tall blazing star and Canada goldenrod and acquired at least a nodding acquaintance with milkweeds, sunflowers, and some of the other more common and colorful wildflowers. At least as importantly, I learned to associate such glorious birds as marbled godwits and bobolinks with patches of native prairie, which even then were mostly confined to very hilly, very rocky, or very sandy sites at the very edges of or beyond what was once glacial Lake Agassiz, the heart of the Red River Valley. I much later learned that such relatively rare prairie plants and animals are “indicator species” and that if one wishes to find them (and protect them), it is necessary to protect the entire prairie community.
When I came to Lincoln in 1961 there were still dozens of relict prairies near town, where I could go to see the prairie birds and plants of my childhood. But as the years passed, these prairies were converted one by one to agriculture or suburban developments, like disappearing Cheshire Cats. But these disappearing cats usually didn’t leave so much as a smile. A few scattered teeth were often all that remained, in ditches and at the edges of fields, where the deep roots of perennial grasses like big bluestem allowed them to continue for a time their losing battle against plows and herbicides. Even the fairly new house we bought at the then-outskirts of Lincoln still had a few shoots of big bluestem that fought valiantly for a few years against the socially acceptable bluegrass. After being warned by the authorities about tolerating such “weeds” in my yard, I too accepted defeat.
One of the few remaining public-access prairies near Lincoln persisting into the twenty-first century is Nine-Mile Prairie, a once privately owned pasture of some eight hundred acres on hilly glacial moraine that had been studied intensively during the 1930s by Professor John Weaver and his students. During World War II part of the prairie was taken over by the military for use as an ammunition storage site, and its size gradually diminished to somewhat more than two hundred acres. The prairie was acquired by the University of Nebraska in 1983 and is now protected and managed both for research and as a historic prairie. It is freely available to the public for nonconsumptive purposes, such as nature study, birding, and hiking.
By a stroke of good fortune, and some ambitious money-raising on the part of the state and local chapters of the National Audubon Society, a large tract of prairie was acquired in 1998 that is just three miles south of Denton and less than twenty miles southwest of Lincoln. This prairie is also located on unplowed glacial moraine and is almost as botanically diverse as Nine-Mile Prairie. Spring Creek Prairie Audubon Center is now the jewel in Nebraska’s prairie crown, with a modern interpretive center and a staff including several trained biologists. Originally 626 acres in area, local fundraising has brought the prairie’s total acreage to 840 acres, of which about 650 acres comprise native prairie.
The flora of Spring Creek has now been well inventoried, and it includes over 370 plant species. Excluding trees, aquatic plants, and woods-adapted plants, there are well over 200 prairie species. Although the majority of the individual plants are perennial grasses, grass species actually make up only about 20 percent of the native prairie floral species diversity. Broad-leaved herbs, which are collectively called forbs, constitute about 70 percent of the species, while shrubs and a few woody vines add the remaining 8 percent. So it is the forbs that give the greatest structural complexity to prairies, and these include a large number of plants in the sunflower (aster) family, fewer in the legume family, and very few in such families as the orchids, only one of which is known to occur at Spring Creek. While the grasses are wind pollinated, many of the forbs are pollinated by insects, and it is this latter adaptation that has produced the displays of multicolored and scented flowers in spring and summer that at times turn the tallgrass prairie into a garden. At Spring Creek Prairie the flowering of the purple coneflower in June and July is a summer highlight, while several asters, such as New England aster and other blue to purple asters, vie with downy gentians to be the final fall hosts to honeybees and bumblebees during late October.
I confess that spring is my favorite time to visit Spring Creek, when the migratory birds are returning and the first spring flowers, such as violets, rush into bloom to complete their flowering before being shaded out by the earlier grasses and taller forbs. But each season has its attractions. The tall prairie grasses are nearly all “warm-season” species, waiting for the oppressive heat of midsummer to put on their most rapid growth. By September the Indiangrass and big bluestem may easily exceed six feet in a wet year, and to lie down in a stand of these grasses and look toward the sky above is to get an ant’s view of its world.
The tallest hills of Spring Creek Prairie are among the highest points in Lancaster County, affording a spectacular, unobstructed view in all directions. Sitting on one of these hilltops one can close one’s eyes and listen to the sounds of near solitude, sometimes marked only by the songs of a distant western meadowlark, the scream of a soaring red-tailed hawk, or, in spring, the soft kettledrum sounds of courting greater prairie-chickens. In 2008 the spring equinox happened to fall almost exactly on the night of the full moon, so I decided to watch the simultaneous sunset and moonrise from the top one of these tall hills. I sat on a large quartzite boulder that protruded a few feet above the ground, a souvenir of the melting glacier that had shaped these hills during the last ice age. It was like watching one beautiful curtain fall in the west as another, equally stunning, curtain was rising in the east.
By November the prairie has quieted down, with the starches, sugars, and other carbohydrates that were manufactured by perennials during summer now safely stored in root systems many feet below ground, well out of the reach of grazing animals. What is left are the rusty brown skeletons of leaves and stems that make for spectacular fall panoramas, especially when contrasted with the red leaves of shrubby sumacs and the blues of cloudless fall skies.
Winter is a time for hardy souls to walk the prairie trails in search of snowy tracks marking the passage of coyotes, rabbits, deer, raccoons, mice, and other mammals that otherwise are likely to remain hidden. Much of the activity of small rodents occurs under deep snow; its insulating quality allows the temperature at ground level to remain only a few degrees below freezing even if the air temperature above the snow should approach zero. Red foxes, coyotes, and some owls can hear the sounds made by unseen mice and voles as they scurry about unseen and will suddenly pounce on them from above. By December the long blue shadows of grass cast on the snow by the pallid winter sun provide only cold comfort, but they do offer the promise of a sun that by January will be rising sooner, slowing increasing in strength and providing both life-giving light and heat to the waiting plants and animals.