Untouched by plows, prairie serves as lab for biology research
Columbia Missourian, Nov. 21, 1980
Protected behind a wire fence and human concern is a fragment of tallgrass prairie, once part of thousands of acres of grassland that covered as much as half of Missouri.
The fading sign on the locked entrance gate says "University of Missouri, Native Prairie Research Area, No Disturbance Please, No Firearms." But the welcome mat is out for people interested in a closer look at a piece of prairie never touched by a plow. No other tract as large is left in central Missouri.
Only 15 miles (24 kilometers) east of Columbia along Interstate 70, few drivers recognize the importance of the tangled grass of the 146-acre (58-hectare) Tucker Prairie. Compared to surrounding fields, now green with winter wheat, the prairie looks unkempt and wasted.
But to Clair L. Kucera, University biology professor, the land is valuable as a research center, a teaching laboratory, and an outdoor museum. Kucera was instrumental in urging the University to acquire the land in 1958. He has spent more than 20 years studying its intricate energy transformations and plant and animal relationships.
There are signs of research activity throughout the prairie. Near the gate, white-painted metal arms extend from a green, metal-clad storage building, tracking temperature, wind, carbon dioxide, and solar radiation.
A brightly colored, three-winged radiation symbol attracts attention to a small plot beside the building. Using a radioiostope as a tracer, investigators determined that, on the average, root systems are replaced every four years. They calculated that it takes 105 years for decaying plant material to form the top layer of soil.
The thick, fertile soil of this prairie contrasts with the thin, stony soil of prairie areas still left in southwestern Missouri. However, the topsoil is underlain by a layer of heavy clay which contributes to wide fluctuations in soil moisture. During the rainy season, the prairie is soggy, while the clay hardens the soil during the dry season.
Scattered among more than 200 species of grasses and other plants are various markers, including cement posts and clusters of little colored flags, that designate projects still under way or areas to be burned.
This year the grasses do not tower over a visitor's head but reach just to the knee. The prairie's plants survived the summer's heat and drought by growing less, but they were still green while corn and other crops shriveled and burned in the sun. Conservation was their key to survival.
It is difficult to imagine what the prairie was like hundreds of years ago. Only near the center of the land, looking north toward the highway, is the surrounding hedge of trees hidden and the traffic noise muffled. Then the horizon becomes a golden-brown, grassy fringe, and the crisp, dry sound of the wind in the grasses, like the sound of millions of tiny bursting bubbles, becomes dominant. Careful listening reveals rustling noises of unseen mice, shrews, and moles scurrying among the plant stalks.
There are also intruders near the prairie center. Young trees have established themselves in an area that has not been burned recently. Without fire, the prairie would turn into a woodland. To keep trees out, research has shown that burning must occur at least every four years.
Woody vegetation has also invaded along creek beds. Here the soil is more moist, and fires are not hot enough to kill the red cedar, elm, and black cherry. In central Missouri, prairies were located between forest-lined water courses.
Prairie projects include study of energy
One of the most important Tucker Prairie projects deals with the flow of energy in the ecosystem. Plants are the originating sources of energy. The stability of the system depends on how the energy is dissipated above and below ground.
If energy is allowed to pile up in the form of decomposed plant material, called litter, grasses disappear, and other plants appear in their place. Fire removes the excess litter and helps maintain the energy balance.
In the fenced portion of the prairie is an experiment to observe the effect of large, grazing animals on prairie vegetation. Under natural conditions bison filled this role, but the fences could not hold these animals. Domestic cattle are now invited to dine.
Light grazing tends to maintain a high plant diversity, because no single plant can overwhelm others without being cropped back. Cattle tend to show better weight gain over a season on native prairie pasture than on single-grass pasture systems.
This is probably a result of the greater diversity of grasses (35 species), each having a slightly different period of maximal growth during the summer. Thus, the cattle can choose the grass that is the best forage at any given time, whereas in most pastures cattle have a limited choice.
Nature's strategy is to allow a large number of species to occupy a certain space and grow side by side, Kucera says. If all the plants made demands at the same time, the prairie could not support them. Instead, each plant "takes its turn," leading to an efficient and productive system.
Jody Rapp, senior research laboratory technician at the University, has spent four years working on various projects at Tucker Prairie, including two summers with Deborah Rabinowitz, a professor at the University of Michigan, who comes down to study prairie grasses.
At randomly selected sites marked by numbered and tagged metal rings, they count the number of flowering stalks from seven grasses, four rare and three common species.
Their surprising conclusion is that the rare species are not affected by environmental variability as much as the common grasses. This year, despite the drought conditions, the rare grasses produced the usual number of flowering stalks, while the common grasses had a reduced number. This research could provide clues for managing endangered plants.
Looking at the products of evolution and how they work to achieve stability in the prairie is important in determining how to restore land such as that damaged by strip mining. Direct comparison shows the strip-mined areas are arrested, harsh, acidic landscapes with wide temperature fluctuations and a great deal of water runoff, in contrast to the more stable prairie.
Kucera says human systems tend to be unstable and points to the devastating effects of single crop cultivation, including extensive topsoil loss and fertility reduction.
"Topsoil is our single most important resource," he says.
Prairie studies are also important because they provide a benchmark. Tucker Prairie soils, for example, can be compared to adjacent cultivated or strip-mined sites with similar initial soil conditions. The prairie soil profile shows the way it used to be.
The Tucker Prairie and similar sites represent a unique habitat which harbors species occurring nowhere else. More than a community of grasses, the prairie includes orchids, gentians, lilies, and many other rare plants.
In May 1975, Tucker Prairie was designated a national natural landmark, one of 10 in Missouri.
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