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A PRACTICAL GUIDE TO PRAIRIE RECONSTRUCTION
By Carl Kurtz
UNIVERSITY OF IOWA PRESSCopyright © 2013 Carl Kurtz
All rights reserved.
What was the tallgrass prairie? Why should we care about reconstructing it today?
What will this guide accomplish?
No living person today remembers Iowa when tallgrass prairie—a highly diverse community of drought-tolerant grasses, sedges, and wildflowers—stretched from the Mississippi to the Missouri River. Botanist Daryl Smith has written that nearly all of Iowa's original prairie disappeared in the seventy years between 1830 and 1900, when settlers moved into the state. Most of North America's 224,000 square miles of tallgrass prairie had met a similar fate by 1930.
By 1910 most of Iowa's 28 million acres of tallgrass prairie, more than 80 percent of the state's total land area, had either been plowed under or would eventually be destroyed by overgrazing. Today less than 2 percent of Iowa's original tallgrass prairie exists as relicts along roadsides and railroad rights-of-way and in old cemeteries and state preserves. Although some people still view prairie plants as weeds, a growing number are committed to bringing tallgrass prairie back to the Midwest.
In this newly revised edition of A Practical Guide to Prairie Reconstruction, as in the first edition, I outline the procedures and problems that you may face in the process of reconstructing a tallgrass prairie, whether it be in your backyard or on your back forty.
The term "reconstruction" means starting prairie from scratch in a bare crop field. "Restoration" is the process of reclaiming grasslands that have been degraded from heavy grazing or lack of management but that still retain remnant populations of native prairie plant species. Both processes require restoring a diversity of native grasses, sedges, and forbs (a collective name for prairie flowers) and implementing a management plan. This guide will not answer every possible question, since each planting is unique, but it should provide a formula for success under most conditions, even in a very dry year. I have updated all the original chapters, the list of seed sources and services, and the references; replaced the original photos with new photos; and added new chapters covering herbicide use and the procedure for restoring old pastures.
We live on a family farm in central Iowa that was purchased by my father in 1930. It was operated as a typical diverse grain and livestock operation until about 1970. As a wildlife biologist, I wanted to resurrect an old pasture that was severely eroded from overgrazing. In 1975, working with our county conservation board, we planted to a mix of five prairie grass species: big bluestem, little bluestem, side-oats grama, Indian grass, and switchgrass. This planting protected the soil and provided wildlife habitat, but over a ten-year period I realized that without forb diversity, the planting lacked long-term stability.
In 1988 my wife and partner, Linda, and I began planting cropland to local-ecotype seed in the hope that it would provide superior wildlife habitat, protect the soil from erosion, and produce farm income from the sale of native ecotype prairie seed. Unforeseen benefits included a dramatic improvement in soil structure and the restoration of water quality in a small wetland located in one of the reconstructed areas.
While most prairie reconstructions begin with the establishment of warm-season grasses, nature always works toward diversity. Grasslands without prairie flowers (broadleaf plants) have empty root spaces. Nature's mission is to fill in that empty space with whatever is available. If a diversity of prairie forbs is present, they will do the job. If these are absent, weedy and often undesirable species such as Canada thistle will move in. A plant community with a higher diversity of species will have greater stability.
The process of reconstructing and restoring prairie grasslands has made great strides in the past twenty-five-plus years. If land and resources are available, it is now possible to plant a prairie with more than a hundred species that function as dynamically as any natural system. This is especially important since we live in a world filled with introduced species from around the globe, better known to most land managers as invasive species. There is growing evidence that these species invade natural areas more readily where there is low species diversity. Removing them is a costly, time-consuming process and in many cases is not even possible.
Tallgrass prairie is critical wildlife habitat as well as an important element in flood control and stream water treatment. There is growing evidence that prairie stream buffers stop soil loss, while created wetlands remove unwanted nutrients from runoff and tile water. The social and economic benefits of these reconstructions may be critical for future generations.
We hope that this guide provides basic directions and encouragement for individuals with private property as well as for land managers working with government agencies and nonprofit organizations who have taken up the task of reconstructing and restoring native grasslands.
We are deeply indebted to numerous individuals who have worked with us over the past thirty-seven-plus years. They have shared their stories and asked countless questions that have helped us understand the process of reconstruction and restoration of the tallgrass prairie. Interns working with us in our plantings have helped make them remarkably weed-free. Friends have faithfully helped with our seed-bagging operation each fall, while prairie enthusiasts have purchased our seed. This has given us the opportunity to make a modest living while refining the process for success under a broad range of field conditions.
What does today's tallgrass prairie look like? Where can you find one?
What plants does it contain throughout the season?
In order to understand what a prairie is, we first need to define it. The word "prairie" has many meanings. Some consider it an open landscape where the horizon is generally visible in all directions. Whether this landscape is planted to grass, grain, or indigenous vegetation is of little consequence. The word "prairie" may still have other meanings, but for the purpose of this guide, let us consider the definition of tallgrass prairie as follows.
The best examples of remaining tallgrass prairie today are generally referred to as virgin prairie. From a botanical perspective, virgin prairie is a complex plant association that has not been plowed to raise cultivated crops or overgrazed to eliminate most native species. The plant community in this type of prairie developed over several thousands of years and was generally devoid of trees except where there were natural barriers such as rivers, streams, and marshes. Mixed- and shortgrass prairies grew in response to decreased annual rainfall and begin somewhat west of the Missouri River, or the 100th meridian, and extend to the foothills of the Rocky Mountains.
Virgin prairies differ from planted grasslands and open-country pastures because they possess a wide diversity of native grasses, sedges, and forbs. Most plants are perennials: they come up from the same root system year after year using energy reserves stored from the year before. Roots vary in depth and size from species like prairie violets, which may be only a few inches in depth, to compass plants that may be a foot across at the crown and more than ten feet in length. Unlike planted grasslands and pastures, which may contain up to thirty species (but usually have far fewer), most virgin prairies have two to three hundred species in a complex association. The actual number of species depends on slope, soil type, and available moisture.
Virgin prairies often possess a wide array of animals adapted to open areas. The meadowlark and bobolink are typical prairie birds. Bison and elk are typical prairie mammals displaced by settlement.
Keep in mind that this definition of prairie is only to facilitate your understanding of tallgrass prairie reconstruction. In order to reconstruct tallgrass prairie, you should become familiar with the grasses and forbs in a tallgrass remnant. Start by visiting a selected site at least once a month from April through November. If you are unfamiliar with a virgin prairie site in your area, contact your local county conservation board, state conservation officer, garden club, your state chapter of The Nature Conservancy, or the Audubon Society.
The plants of spring are usually short; as the season progresses, later-blooming forbs and grasses are taller. In spring a tallgrass prairie may be only six inches to one foot high. By midsummer it will likely be between three and four feet high, and by late summer some grasses and flowers will be seven feet high or greater. Exceptions to this are species like bottle gentians and ladies'-tresses, which flower during early September at a height of six to eighteen inches, respectively.
Early in the season, there is little color in the dried brown grasses remaining on a prairie landscape. Pasque flowers can be found in the northern half of Iowa and begin to bloom in early April. In late April or early May, you can find a miniature sunflower called golden ragwort, the demure blossoms of blue-eyed grass, and yellow stargrass. The latter two are members of the iris and daffodil families, respectively. Also seen at this time of year is wood betony, which has a twisted head of yellow tubular flowers and soft, fernlike leaves. The flowers of prairie violets are similar in size and shape to those of common blue violets; however, prairie violet leaves are deeply dissected. Later in May, shooting stars can be found.
In late spring, the orange phloxlike blossoms of hoary puccoon and prairie phlox grow among the slender stems of porcupine grass. Porcupine grass, a cool-season species, is also known as needle grass. Its needle-tipped seeds have a long awn that corkscrews as it dries, planting the seed. Canada wild rye is also a cool-season grass that flowers in late spring. Some varieties have bluish leaves that are wider at the base than most other grasses. The seed head, as the name implies, reminds one of rye or wheat.
In late June and early July, the prairie celebration gets into full swing. Black-eyed Susan, pale purple coneflower, and butterfly weed add bursts of color. In late July and August, the warm-season grasses such as little bluestem and side-oats grama begin to flower. On dry slopes, little bluestem intermingles with the striking magenta of rough blazing star. Along mesic (moist) swales, you can often find prairie blazing star, compass plant, and common mountain mint. The leaves, stems, and flowers of mountain mint have tiny oil glands that give the plant a pungent smell when crushed. Big bluestem, also called turkey foot, may attain a height of seven to nine feet in late August. Indian grass and switchgrass extend to their full height and flower in late summer. In early autumn, the deep blue of bottle gentian, which is pollinated only by bumblebees, can be found in swales. Downy gentians favor the drier upland of rich mesic prairies.
Many species of sunflowers, asters, and goldenrods bring up parade's end in September and early October, some flowering well after the first autumn frost. Tall goldenrod, with a plumelike flower head, and stiff goldenrod, with a flat-topped flower head, are two of the most common species. Four species of asters are often abundant in central Iowa. Heath aster has dense masses of tiny white flowers. Smooth aster, as the name implies, has a smooth stem and sky-blue flowers. The white flowers of frost aster are perhaps an inch across and not as densely grouped as those of heath aster. New England aster, which has deep blue or light magenta flowers, likes wet swales and is often found in gardens.
While this is only a sprinkling of the number of species found across Iowa, many occur across the Midwest and are good indicators of native prairie vegetation.
It is not possible to learn all the prairie plants in a single season, a dozen seasons, or even a lifetime. If you begin to look at prairies in your area, you will find that common species are easily identified—and with recognition comes the constant pleasure of seeing old friends in prairie relicts throughout the countryside.
SEED SELECTION AND HARVEST
Why use seed rather than live plants? How many species should you plant?
Where should you obtain the seed?
Seeding a prairie, as opposed to planting with live plants, is the only economical way to establish any area larger than a backyard garden. The greatest problem in planting a prairie is obtaining a diverse seed assortment at an economical price.
We have already mentioned in chapter 2 that prairies often contain two to three hundred species in a complex association. However, most nursery catalogs list only seventy to one hundred species with the seed of some species costing two hundred or more dollars per pound. Is prairie planting actually feasible from an economic point of view?
Research by Robert Betz, a prairie botanist from Northeastern Illinois University, has shown that a relatively small number of a prairie's total species actually comprise a major portion of its standing biomass (the weight or volume of living plants). Thus, a reconstructed prairie can have many features of a virgin prairie with about 10 percent of the total species. This is not to say that the remaining 90 percent are not important, but in many cases they occupy little actual space.
We have had the most success with the species listed on pages 13 and 14. Try to obtain as many of these as possible, and try to use at least thirty species. Many species can be hand-collected in small quantities. Be sure to obtain permission before collecting in any area, and above all do not dig plants from any area unless they are about to be destroyed by development. It is far easier to plant your prairie from seed than from transplants. I have rescued a few plants in the past twenty-five years from abandoned railroad rights-of-way. It was backbreaking work with meager results.
Much has been written about the use of local seed types. A local-ecotype seed is one that naturally evolved on or near your site. Some individuals consider seed to be local only if it is produced within ten miles, others thirty miles, and still others seventy to one hundred miles from your location. Because prairie plants that evolved locally are adapted to the climate of your area, the seeds they produce are certainly the best choice.
Some prairie enthusiasts are very firm about using local-ecotype seed and are concerned that seed from out of state may weaken local genetic stock. Botanists too are especially concerned about genetic purity near state prairie preserves. Because the market for local-ecotype seed is increasing, it appears that more will be produced to meet the demand. When purchasing seed, be sure you know its source origin and whether it is certified for viability by a seed-testing laboratory.
Will seeds that are not locally adapted work in your planting if local-ecotype seed is not available? In older plantings, we used some grass species that were of a western or southern origin. A southwest variety of big bluestem almost completely disappeared fifteen years after planting. In another planting, western little bluestem seems to be quite stable after twelve years. The key to success is having as much variety in your mix as possible. I believe that species diversity and local-ecotype seed are both very important if your prairie is to have long-term stability. Diversity fills empty root space at all levels, while local-ecotype seed is climatically adapted to the temperature and moisture regime in your area. Seed that originated in dry areas may be susceptible to fungal diseases where there is higher rainfall and subsequent higher humidity.
Ideally the best way to get a large quantity of local-ecotype seed is to harvest it from a virgin prairie remnant using a grass stripper or a small combine. For many years we have harvested part of a twenty-acre virgin prairie with an old Allis-Chalmers pull type combine. The main modification needed is to block most of the airflow beneath the sieves. This prevents the loss of light, fluffy seeds such as those of goldenrods and asters. Harvesting takes place in the fall when the stems and leaves of the grasses and flowers are dry enough to be thrashed (usually early to mid October in Iowa). The harvested seed mixture will contain broken stems and leaves. Since shattering takes place when the combine reel strikes the seed head, you will not get all the seed from each plant. If there is a slight breeze, seeds of all types will flow freely from the combine header and over the tailings sieves. Our best harvests have produced 10 percent seed in bulk mixes from virgin prairie sites. Weather is a big factor, however, and after a very dry and hot summer we have seen the percentage of seed in the mix fall below 2 percent. Generally we do not process or clean mixed seed. This is labor-intensive work and does not improve seed quality. For best results, store seed in a cool, dry place that is free from mice. Storing seed in jars would be good for mice, but if it was not dry it could mold. If it is in paper bags, any moisture in it will evaporate. We store our seed in brown paper bags or in woven poly-plastic, which breathes.
We have also hand-gathered seeds of species such as prairie phlox, spiked lobelia, flowering spurge, Indian plantain, golden ragwort, and cream gentian and added them to our bulk mixes with good results.
How did prairie soils develop? Will prairie plants grow equally well in rich and poor soils?
Prairie soils, which support today's agriculture so successfully, developed over a period of thousands of years. Research by David Montgomery, cited in the July 2008 issue of Scientific American, indicates that topsoil formation is a very slow process; it can take from 700 to 1,500 years to form an inch of soil. Before cultivation, the growth and subsequent death of the roots and crowns of prairie plants form humus in the upper soil layers, giving them a dark brown to almost black appearance. Humus mixed with fine clays and sand gives soils the ability to hold water and nutrients and keeps them friable (somewhat loose and crumbly). When soil is moist, you can press it between your thumb and forefinger, and it will break apart easily. Virgin prairie soils may have a topsoil layer that extends eighteen inches below the surface.
Plowing of prairies and subsequent agricultural use oxidize the humus, leaving the soils less able to hold water and nutrients. The erosive action of moving water on an unprotected soil surface also removes organic material in the form of silt. Silt floats in a watery suspension and is carried by heavy rains to rivers and streams, where it is deposited in lakes, reservoirs, and quiet river backwaters.
Some prairies started the soil-building process on glacial till, a mixture of rock ground by glacial ice into a flourlike consistency. Other prairies began on loess deposits, which consist of fine wind-blown particles lifted from major river and stream valleys, formed during a period when glaciers were receding.
Excerpted from A PRACTICAL GUIDE TO PRAIRIE RECONSTRUCTION by Carl Kurtz. Copyright © 2013 by Carl Kurtz. Excerpted by permission of UNIVERSITY OF IOWA PRESS.
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