Prairie Management and Restoration in Iowa
Brian Fankhouser, INHF's Bufflands Program Manager, at a goat prairie in eastern Iowa. Click here for a video of Brian explaining this special landform.
Photo credit: Hannah Inman
By INHF staff member, Marlene Ehresman, and Iowa prairie expert, Carl Kurtz.
What is a prairie?
A prairie is a community of grasses, forbs (wildflowers), shrubs, animals, and microorganisms. Prairie can be found as far east as Indiana and as far west as the Rocky Mountains. Its northern reaches extend into Canada and can be found as far south as Texas. Historically there were over 30 million acres of prairie in Iowa, but agricultural and urban developments have drastically reduced this amount. In Iowa, 150 years ago, nearly 85% of the state was tall grass prairie. Today less than 0.1% of this prairie remains.
Prairie ranges from the short grass prairie of the western plains, which grows less than one foot tall, to the tall grass prairie of the Midwest, which can grow to heights of seven feet. Within the tall grass prairie there are three broad types of prairie - dry, mesic, and wet. In a wet prairie you might find big bluestem or compass plant while in the dry prairie you may find sideoats grama or pale purple coneflower. As the names imply, these types of prairie are dependent upon the moisture available, both in the amount of rainfall and the amount that is available in the soil. More porous soil and hilltops tend to have dry or possibly mesic prairies and the bottomlands are usually dominated by mesic or wet prairie.
The environmental conditions in a prairie can be extreme: intense sunlight, late spring snows, and high winds. Up to two-thirds of a prairie plant is contained below ground in its root mass, which helps the plant tolerate these extreme conditions. The roots help the plant take up nutrients and water from the soil. Buds on the roots allow regrowth after fire burns the tops off the plants. Another strategy some of these plants have developed is to have little hairs on the leaves and stems to conserve water from the evaporative effects of the hot sun or windy days. Other plants have developed toxins or spines to prevent them from being eaten by deer, rabbits or insects.
The prairie varies seasonally both in color and height. Early in spring the prairie is much shorter with some small wildflowers blooming. The prairie reaches its peak color in July when most of the forbs are blooming. Later in the season, the prairie is dominated by tall grasses, which give the prairie its beautiful fall color of orange, brown, and purple.
Why is prairie important?
Prairie is a part of our heritage in the Midwest. It has created the beautiful and productive soils that dominate Iowa. The prairie provides wildlife habitat. You may see signs of badgers, butterflies, bobolinks, red fox, opossums, northern harriers, jackrabbits, raccoons, American toads, leopard frogs, and many nesting birds. Due to their massive root systems, prairies prevent erosion while rebuilding worn out soil. The predominance of perennial plants in the prairie help control weeds. Since less than 0.1% of our prairie heritage remains, it is important to begin restoring and reconstructing prairie where it is appropriate. In Iowa, prairie has been restored and reconstructed in wildlife areas, parks and preserves as well as on private property by enthusiastic landowners. Other examples of prairie restoration in Iowa are the many roadsides that have been planted with native prairie to prevent erosion, reduce the maintenance costs of traditional mowing, and for beautification.
How do I restore my land to prairie?
First, you need to determine if you are rehabilitating or reconstructing your prairie. Reconstruction means starting with bare soil (such as a former crop field). Rehabilitation means starting on land that already contains some remnant species. Restoration is defined as "the process of bringing back to an original condition," and thus includes both rehabilitation and reconstruction. Anyone planning a prairie project needs to know and appreciate the difference.
When rehabilitating a prairie remnant, it is important to remember that most prairie remnants are highly degraded because of neglect or abuse. However, with some moderate restoration and proper management, they may be turned into healthy functioning ecosystems. For example, removing invasive exotics, woody vegetation, or other undesirable species may be appropriate. Restoration practices to remove these undesirable species include physical removal with saws, burning, hand weeding, mowing and in some instances selective applications of herbicides. It may be appropriate to return absent species by interseeding them or transplanting seedlings into the remnant. Contact a restoration professional to help you identify what is in the remnant and develop a restoration plan.
In reconstructing a prairie the first thing you want to consider is what you are trying to accomplish with your prairie. Do you want the prairie to be purely an aesthetic wildflower garden or do you want it to be an ecologically functioning prairie? A wildflower garden may look like a prairie but usually does not have the diversity or size to function as a prairie.
Some sites may not be suitable for prairie restoration, so you will need to consider the suitability of the site you want to restore. For instance, what are the soil types? Soil is very important in the successful return of the prairie. Moisture and topography are also very important. These physiographic conditions will help determine what type of prairie plants should be used in the restoration - dry, mesic, wet, or a gradient of these prairie plants. The history of the site can give you some indication of the type of prairie you should plant. Finally, consider the surrounding land uses as they can directly affect the success of your prairie.
It is best if you let the area that you want to return to prairie lie fallow for a year to observe the site characteristics and any problem plants that might exist, including exotic species such as reed canary grass, brome grass, Canada thistle, and purple loosestrife. Waiting will also give you time to collect the materials you will need. During this time visit a local prairie. It will help you get a better understanding of prairies as you undertake establishing your own prairie.
Soil and Site Preparation
If you are constructing your prairie from plowed ground, it is important to consider preparation of the soil. Tilling the soil 2-3 times before planting will reduce the amount of weed competition. Tilling should begin as soon as the soil will allow it, usually April, and occur approximately every three weeks until planting. Tilling should be shallow, less than two inches, as deep tilling will bring more weed seeds to the surface.
A good seed source is also very important. If you are restoring a prairie, make sure that you are using plants and seeds that are native to Iowa and the region. The use of local ecotype seed should be considered. Ecotype refers to the genetic make up of the prairie plant or in this case prairie seed, while local refers to less than fifty miles from the site being restored. Prairie plants of local ecotype have co-evolved over thousands of years to the local climate conditions and often they developed resistance to local pests and diseases. This is important to the vitality of the prairie being restored as prairies planted with non-local ecotype seed may not have the same resistance. Local ecotype seed is important to local wildlife like butterflies that are specialized in the plants they pollinate. Further, not using local ecotype seed will contaminate the genetic diversity of the remnant prairies that remain in Iowa.
Seed can be obtained from many nurseries in Iowa and surrounding states. Some of these nurseries have local ecotype and some do not. Make sure to ask the nurseries how and where they got their seed. Be alert because some dealers may stock seeds from other states or may stock horticultural varieties of the prairie plants. Horticultural varieties have been genetically altered to bring out a particular characteristic of the plant such as color or size. Like non-local ecotype, they should be avoided in prairie restorations.
Your seed mixture and application rates will depend on the soil types, goals, and budget; your distributor can help you with this. Seed is measured in terms of Pure Live Seed (PLS). You should aim for approximately 10 pounds of PLS per acre of prairie. Remember that the more diverse the prairie is the better. It is recommended that there be at least 35 - 40 different species in the mix, but more diversity is always better. Historic prairie surveys and remnant prairie surveys have found over 200 species in Iowa prairies. However, the more diverse the prairie planting is, the more expensive it is.
The most appropriate planting method depends on the size of the prairie and the resources available.
A prairie can be planted either in the spring or in the fall. Spring planting should occur after the ground temperature has reached 55ºF, which usually occurs in April in Iowa, until the end of June. Some Iowa restoration specialists recommend that you wait until at least May 1st to begin planting. Although there has been greater success with spring planting by many restorationists, fall planting, late October through mid November, is also appropriate. In fact, some forbs respond better in fall plantings. However, high winter mortality of the seedlings and predation of the seeds during the winter can reduce the success rate of fall plantings.
Management of your reconstructed prairie
First year - early establishment: About three weeks after the prairie is planted for a spring planting or around June for a fall planting, begin monitoring the prairie for weeds. Once the weed growth reaches a height of ten to twelve inches, mow with a sickle or rotary mower back to two to four inches. Repeat about every three weeks depending on the rain and height of the prairie until mid September. Gradually increase the mowing height to eight inches.
As the prairie becomes more established, it will begin to choke out the weeds. During the second year, weeds will likely still exist in your planting. The best maintenance for the prairie during this time period is manually removing the weeds; however occasional mowing may be necessary to reduce weeds when the grasses are not well established. The prairie should be mowed no shorter than eight inches. Some weeds are particularly difficult to remove such as Canada thistle or curly dock, so a herbicide may need to be used. Contact your local county conservation board or county weed commissioner to determine which herbicide is appropriate. Do not be discouraged, some plants may take a while to establish and even longer to bloom.
The prairie planting is ready for its first burn. The roots of the plants should be developed enough that the plant can withstand burning. Burning should be continued for the next 3 to 4 years or until the prairie is well established. Establishment will vary on each site and depends on the weather from year to year.
Burning is recognized as a management tool for prairies but is also very helpful during the restoration and reconstruction of a prairie. Burning stresses exotic plants and creates microclimates more suitable for the native prairie plants. The time of year and frequency of the burns will depend on the goals of the burn. Most prairie restorationists feel it should be burned every two to four years once established. If the prairie is large, burn no more than 1/4 - 1/3 of area to reduce the amount of wildlife habitat disrupted or destroyed with the burning. To be the most useful, burns should occur in early spring from the last week of March through the first part of May or in late fall from September to October after the growing season has ended. Although spring burns are most often recommended, burning too early may injure early blooming plants and stimulate unwanted growth of sweet clover and Queen Anne's lace. If you are burning for the first time, get more information from your local county conservation board, NRCS, or local Iowa Prairie Network chapter.
Mowing can be used as an alternative where burning is not allowed by local ordinances. When mowing, remove plant residue so that it doesn't smother desirable prairie plants and seedlings. If the exotics persist, a herbicide can be used.
Exotics are plants not native to Iowa. They are often called weeds; however, a weed just means that it is an undesirable plant, but it may be native to Iowa. Exotics pose a large risk to the prairie, especially a young or severely degraded prairie, because they compete with the more desirable prairie plants for resources. An annual ground cover like rye may be used during prairie establishment to reduce unwanted exotics. Further, many weedy species are annuals and can be removed through a couple of burn cycles or manual removal. Some however, are much more difficult to remove and can be removed with selective use of herbicides. To learn more about appropriate herbicides, contact your local county conservation board or county weed commissioner.
There are programs available to help in prairie reconstruction. The Conservation Reserve Program (CRP) is through the USDA. Through the program, eligible land is retired from row crop production for a period of 10 - 15 years and can be planted in native prairie grasses. The landowner is paid a rental rate for the land and is typically reimbursed for 50% of the expense of the native grass plantings. A second program is offered by the Iowa Department of Natural Resources Resource Enhancement and Protection (REAP) program. It is managed by the county soil and water conservation districts in Iowa, which can be contacted for more information.
The key to restoration is to be patient. Start small. It is a slow process and may be frustrating and disappointing, especially in the first years of establishment. But the rewards of a healthy prairie are definitely worth it.