At this time of the year, it's easy to look out your window and see a lot of nothing. Leaves have fallen, crops have been harvested, and grass has dried up to a monotone of yellowy brown. Looking at all this seeming death tends to sap the imagination, and not invite second looks. Instead we wait for spring, and for the glorious green to return to our part of the world.
But there's something there, beneath all the crispy remnants of the summer, quietly carrying on with its business while most of us wish we could curl up and hibernate through the chilly months of winter. If you farm or garden or otherwise manage land, it's probably already on your mind. It is the soil; the ground beneath us from which all life and sustenance comes. And what exactly is it doing under there anyway? That brings us to the topic of this article, but first, a bit of history.
The vast majority of our soil was deposited here thousands and thousands of years ago by glaciers (called till) and wind (called loess). Then came the trees and then, after the new Rocky Mountain range began ringing much of the rain out of the eastward-marching clouds, the trees died and the prairie, made up of much more drought-tolerant plants, grew to replace them. The growing and dying of these fascinating plants, along with all the tiny organisms the help them decompose, are largely responsible for creating the rest of the rich soil we associate with prairie. Let pass thousands more years, and you have a stable plant community that has evolved not only to withstand grazing, frequent fire, and unpredictable weather, but absolutely flourishes in these conditions. These plants can still be found at Kankakee Sands and other preserves across the area known as the Great Plains.
Above ground, a healthy prairie is a beautiful mess of colorful flowers and waving grasses. What we see, however, is only about one quarter of the actual living plant material! The rest of it is underground, and this is the key to its hardiness. During the winter months, or in times of high stress such as drought or fire, many of these plants (especially perennials) can essentially withdraw all their energy into their roots, protected, until growing conditions are more favorable.
Down in the earth, the plants have everything they need. The dead plant materials from winters passed have decomposed or burned, leaving an ample supply of carbon. The multitudes of fungi and bacteria in the soil add nitrogen, either by decomposing themselves or by converting the nitrogen in the air into an organic form that plants can use. This process is called “nitrogen fixing.” Also in the soil waiting patiently for their time to come are millions of seeds. Many of these seeds require a winter's worth of cold before they can grow, and some require several. While most plants make seeds, some have other means of reproduction, also with the help of the soil. These plants form what looks like a large horizontal root, called a rhizome, out of which new shoots can grow. With rhizominous plants, what appears above the surface as several plants can actually be one individual.
Soil can generally be grouped into one of three groups - wet, medium (or “mesic”), and dry – each soil type producing different mixes of plants. Areas with medium soil are the best for farming, and so the most endangered. In upland and medium areas where the soil is dryer, the mass of underground plant life gets oxygen with the help of burrowing ground animals, like pocket gophers. Tunnels and burrows create pockets in the ground that aerate the soil. In water-logged areas it is much harder for plants to get oxygen, and wetland plants have adapted to these conditions in a few different ways. Some grow their roots much shallower in the ground or send their roots out of the water to benefit from dry periods where they may be exposed to the air. Some plants have abnormally large cell walls, built to keep the interior of each cell dry and able to function as it should.
At the Efroymson Restoration at Kankakee Sands, we strive to maintain lands that represent the full range of soil types. One can find all types of plants, from the moisture-loving to the dry-loving. These plants, above and below ground alike, support wildlife. Pocket gophers, slender grass lizards and leopard frogs are all species of special concern in Indiana. Also found here are dozens of species of grassland birds including the marsh harrier, as well as game species such as quail, turkey and deer. These and so many more call the prairie home. And it all comes from what's there, always under your feet. The soil. -Bria FlemmingAugust 02, 2013