Objectives For Prairie Management:
The purpose of prairie management is to preserve and enhance the natural qualities of the prairie and its biodiversity.
The management of prairies includes the simulation of the natural mechanisms that have allowed the prairie to survive to out time such as grazing, fire, and at times lack of these influences. Other factors include weather and geological and zoological agents. Management also includes active human intervention such as domestic grazing, mowing, and haying as well as manual, biological, and chemical means of selectively removing undesirable species. Passive techniques include monitoring sites that do not require intervention, fencing, and providing buffer areas.
Influences such as grazing, fire, soil disruption, weather change or nonintervention will cause certain species to respond either beneficially or negatively. Management techniques should be chosen for their beneficial effects. Such management techniques should be carefully applied to small portions of each biological community, so as to leave a refuge for species which may be harmed by the given management technique.
Historical Features Related To Prairie Management
In general, prairies thrive by occasional influence of grazing and fire. Without such influences, the prairie grasslands progress by succession to poor quality woodlands.
Grazing is a natural phenomenon. Herbivores are an important component of the prairie ecosystem. Their natural actions include: grazing, uprooting and trampling vegetation, wallowing in mud holes, and creating hoof depressions. They cause considerable damage to woody vegetation by browsing, gnawing, and rubbing. Grazing, like fire probably was fairly random and irregular, although sometimes locally intense and repetitive.
Fire patterns were probably patchy, random, and irregular, depending on wind, temperature terrain of the land, and the amount of fuel left by grazers. Some fires were started by Native Americans. These factors would have left unburned swaths of land, which allowed the survival and enhancement of species adversely affected by fire.
It is worth noting that many of our high quality prairies survived modern settlement most often by one of two means. One way was cutting the prairie for hay one or two times per year. The other way was light intermittent grazing. Most had a component of neglect and a lack of active management. Many had very infrequent fire exposure between settlement and modern day active management.
Original fire and grazing patterns remain undetermined. Soil surveys, historical accounts, tree ring studies, and land surveyors' notes are used to help identify original biological components, and fire and grazing patterns. These finding may not represent original pre-1700 conditions due to dramatic culture influences and reduction in grazers during transitional times (1700's, 1800's). The reduction in grazers may have caused flammable biomass buildup resulting in more frequent fires during traditional times.
Today, our prairies are fragmented and isolated from each other. Such fragmentation prevents the natural free flow of seeds, animals, and other genetic from one prairie to another.
General Management Guidelines
- A biological survey should be taken of all major plant and animal groups, and updated regularly. Contact the Iowa Prairie Network, County Conservation Board, or State DNR natural areas staff for individuals to help with surveys.
- A Specific plan with goals should be established for each prairie. Take into account management need, problems, alien species, threatened and endangered species, availability of help (manual labor, equipment), and adjacent land use. Make maps.
- Treat only small portions of the prairie (fire, mowing, grazing). Avoid single universal treatment of a prairie tract so as to avoid extirpation of species and to minimize other negative effects on susceptible species.
- More specifically, divide the prairie into biological communities. Allow only a fraction of each community to receive disturbance (by fire, grazing, mowing) each year. The purpose of this action is to leave a refuge for species which may not be harmed by the given management technique.
- Diversify treatments. Treatment techniques as well as time of application should be varied, from year to year, for each given community.
- Gain control over unwanted woody vegetation by manual removal so that subsequent re-growth can be more efficiently controlled by use of a tractor mounted mower (and grazing and occasional burning).
- Record past and present influences and management techniques. Record the effects of management . Evaluate and revise the management plan regularly.
- Some prairies have a low need for management and should be left alone as a type of management.
- Plant and animal specimen collection and seed collection should be regulated so that it does not harm the prairie community. Legitimate benefits of specimen collection include enhancement of local native prairies, and research that will provide increased public knowledge.
- Do not introduce wildlife cover, food plots, or alien trees.
- Introduction of native species; Introduced genetic material should be locally derived as well as site and soil specific. The side of origin should be recorded. See "INTRODUCTION OF NATIVE SPECIES".
- Use small segmental burns. The prairie should be broken down into biological communities. Each biological community should be divided into five or six patches with representative biological components in each patch. Burn one patch (subsection) per year, maximum. For example, a prairie with a dry knoll and a mesic plateau should have only a small portion of the knoll and a small portion of the plateau burned on a given year. Utilize strips which traverse the small portions of each community.
- How often should you burn? Consider every 10 years combined with mowing and grazing. Standard burn cycles are often 2 or 3 years; however, negative effects of fire and possibility of species extirpation have resulted in suggestion of 10 to 30 year cycles. Leave some sections burn free permanently. Black soil prairies with high biomass production may require more frequent fires than dry, sandy, or rocky low biomass prairies.
- Burn in long linear shapes. This method provides a longer border for slow-moving species with several year recovery times to repopulate.
- Avoid burning contiguous parcels in consecutive years. This play allows species to repopulate. Use multiple strips.
- Avoid re-lighting areas that were skipped by burns. These areas provide a natural refuge for species harmed by fire.
- Minimize backfires since these may result in a longer exposure to a hotter fire at the surface.
- Create fire breaks by moving the breaks the summer before the burn. This practice allows for disintegration of debris and hence cleaner breaks and less labor into raking away debris. Fire breaks can be created by mowing, hand brush cutting, plowing adjoining non prairie land, or by using roads, creeks, paths, etc.
- Vary the timing of burns. Invading alien cool season species are commonly battled with a spring burn after the alien species have leafed out and greened up. Consider varying the time of burns, so as not to artificially select spring burn favored communities.
- Consult other sources for specific burning techniques.
Large herbivore grazing should be considered for occasional, brief periods of intense grazing (simulation natural grazing) on small subsections as delineated under "FIRES". Livestock should be quarantined for two days with weed free hay prior to their introduction onto the prairie in order to remove seeds from their digestive system. Prairie grazing increases efficiency of farming operations due to high nutrition and relieving pressure on cool season pastures.
Native species (bison, elk) are recommended for grazing. Availability and practical concerns presently limit this choice. Prairie managers need to encourage the improved availability and use of native herbivores. Site specific herbivores can be considered (bison for open mid and tall grass, elk for savanna).
Domestic grazers such as sheep and cattle are less desirable; however, they will work for short periods of grazing. Domestic animals feed differently than native bison, elk, rabbits, prairie dogs, insects and other herbivores. For example, bison preferentially feed on grasses whereas domestic grazers selectively reduce some flowering species. Cattle grazing will yield a different, less natural biological community than bison grazing.
Mowing / Haying
Mowing and haying simulate some features of grazing and are helpful and efficient in treating large areas of woody vegetation and alien weed overgrowth. Consider occasional mowing and haying during the growing season on small subsections as delineated under "FIRES". Prairie hay is desirable for livestock feeding.
We also need to consider the effects of soil disturbance. Some species thrive with soil disturbance from burrowing or uprooted trees.
- General Issues: Cut or mow after plants have been fully leafed out (energy stores above the ground) but before they have trans-located significant winter stores to roots- perhaps mid June through August. This cutting can be achieved by use of chain saw, brush cutter, pruning shears or a mower on a tractor. Setback of woody species can be maximized by cutting and re-cutting sprouts more than once per year as well as re-cutting in successive years. Removal of lager trees should be done in that winter with frozen ground and snow cover in order to protect the suppressed under-story species.
- The suppressed under-story vegetation may be only sparsely visible initially; however, it will rebound nicely in subsequent years with proper management.
- Trees and medium diameter brush: Ring trees with a chain saw or remove the cambium manually in the summer, and leave standing. Remove trees in the winter.
- Small brush and re-sprouts: Cut and re-cut in summer. Remove from prairie if dense so as not to cover under-laying vegetation, otherwise may leave in place. Consider herbicides for difficult species such as sumac and black locust (see "HERBICIDES").
- Cedars: Cut and remove in winter. No herbicides needed. Cedars are easily killed by fire.
- Brush piles: Create piles on disturbed ground (i.e. previously tilled ground). To not place on grassy areas or on adjacent brushy areas since such areas may spring back to prairie when cleared and managed. If brush is piled there it will sterilize the existing native vegetation, soil, and seed bank and the area will fill with weeds.
- Vines (on trees to be removed): Consider stump treatment with herbicides before the tree is removed so that they don't spread horizontally on the ground after the tree is removed.
- Bison/grazers naturally control woody vegetation.
- Leave some woody plants untouched since they may provide a different local environment for unusual species.
- Annuals and Biennials (bull thistle, sweet-clover, etc.): Cut at the time of flowering in order to remove the reseeding potential. Properly timed fire of cutting may be appropriate. "Pulling weeds by roots" can be effective for isolated weeds; however, keep in mind that disturbed ground left by this maneuver can invite more weeds.
- Perennial weeds: Routine prairie management (mowing, burning) will conquer many weeds.
- Perennial weeds with underground stolons (Canada thistle, leafy spurge, etc.): Stump treatment with 33% Roundup is efficient for small populations. Leafy spurge is a serious problem that can completely overtake grasslands. It aggressively colonizes disturbed areas. Roundup 1 to 2% spray is effective. Some prairie managers use Tordon 22K or a 10% solution of Tordon RTU topically; however, note severe adverse effects in "Herbicides". Yearly vigilance is required.
- Cool season grasses and weeds: Use late spring burns after the aliens have leafed out. Routine management and succession to prairie will set back these species.
Biological Control Agents
Biological agents such as insects are being investigated and utilized against specific problem plants. This method is being studied for its effectiveness against Leafy Spurge and Purple Loosestrife.
Through studies need to be done in order to identify adverse effects on native specific. The user has a responsibility to review and understand these effects.
For assistance, contact the states office of The United States Department of Agriculture (USDA), Agriculture Research Service, as well as university agricultural research center.
- General issues: Herbicides may be required for aggressive species and species that create underground suckers from mechanical treatments. These species include sumac, black locust, leafy spurge, and Canadian thistle. This is especially true for areas without available grazing or mowing capability or lack of labor to administer repeated mechanical treatments.
- Stump treatment is more specifically directed and is considered the safest application technique. Hand wick application is fairly safe; although the potential for drip exists. Spraying causes damage to adjacent plants by drift and should be avoided or used with extreme caution.
- Caution: Chemicals can trans-locate to adjacent plants through the soil and roots. Research regarding herbicide effects on high quality prairies is sparse. Caution should always be taken when using herbicides.
- Specific: Name the herbicide, mode of application, species and area to be treated, time of application, and names of persons who will be applying the herbicide.
- Read the directions with the chemical.
- ROUNDUP – Roundup apparently is broken down quickly and doesn't trans-locate to other species through the soil, which makes it a preferred herbicide. Stump treatment with a 33% solution of Roundup is efficient and should presumably protect surrounding preferred plants. Adjacent plants will die if there is a direct root to root contact. It should be applied sparingly to the perimeter cambium layer of the tree or weed in late summer (four weeks before leaf color change) when trans-location to the roots is actively taking place. Spray (!% to 2%) directed stream spray (5% to 7%), and wick (33%) treatments should be done when the plant is actively growing. Roundup will kill any plant upon topical contact. Spray and wick treatments can cause elimination of surrounding preferred plants by drift and drip. Visible effects of the plant's decline may not be evident for many weeks or longer.
- TORDON – This chemical trans-locates to the surrounding plants through the roots and should not be used on high quality prairies except in extreme conditions, in such cases that the loss of surrounding vegetation is acceptable.
- Other chemicals may be acceptable, and controlled studies of effects on remaining vegetation is welcomed by prairie managers.
Introduction of Native Species
Introduced genetic material should be locally derived as well as side and soil specific. The site of origin should be recorded. Nearby prairies can be used as models and seed sources. Reasons for introducing a new species includes providing a local refuge for unusual species which allowed it to adapt to that site (out-breeding depression). Reasons for supplementing an already existing species includes restoring a declining species, especially if there is a lack of seeds/genetic material from the existing individuals.
Adjacent Land Management
- Inventory, create a plan, and follow guidelines as discussed in "GENERAL MANAGEMENT GUIDELINES."
- Enhance the native, natural qualities of the prairie.
- Create a native buffer zone using locally derived, soil and site specific species (i.e. dry sandy species for dry sandy soil).
- Increase the diversity of habitat in appropriate sites. This practice will allow survival of marginal species that require mixed habitats.
- Enhance habitats for locally rare or extirpated species.
- Remove unnatural features.
- Revive degraded areas that degraded condition promotes unusual species. If the land has not been tilled or otherwise significantly impacted, native vegetation will often return with management. IF, after several years of management, native vegetation doesn't return, then reconstruction of site specific prairie or savanna vegetation and animals may be considered.
- Prevent runoff or drift of soil, weeds, pesticides, and air-born pollutants onto the prairie.
- Do not plant alien, invasive species such as crown-vetch, purple loosestrife, sweet clover, birdsfoot trefoil, pampas grass, etc.
Challenge: Dynamic Communities
Special management is needed for species that thrive in a mobile community such as the woodland/savanna/prairie edge, or a transient community such as that which would thrive in a trampled mammal path.
Mobile communities are moving from year to year depending on the fire, grazing, weather, and other physical pressure that controls their presence. For example, the purple milkweed may thrive on the leading edge of the savanna along with the dogwood and sumac. Nearby, the showy orchid is growing under the advancing May apples and oaks in a semi-closed savanna. The management challenge in these cases is to create and maintain an appropriately staged mobile woodland/prairie edge for such species. Community motion can be created by allowing savanna vegetation to creep gradually onto the prairie. Alternatively, this community junction can be maintained in steady state by cutting woody vegetation and allowing savanna vegetation to creep gradually onto the prairie. Alternatively, this community junction can be maintained in steady state by cutting woody vegetation and allowing re-growth at the same site.
Examples of transient environments include compaction and disruption from deer paths, mammal wallows, mammal burrows, and mammal foraging and rubbing. Such impacts may explain why Great Plaines ladies tresses are sparse on one high quality minimally impacted prairie, while they thrive in an adjacent (mechanically made) road ditch. We need to allow for various influences in the management of prairies, so as to allow the survival of species requiring such various influences. At the same time we need to avoid excessive treatment to allow survival of species harmed by such treatment.
The author wishes to thank the many prairie enthusiasts who have helped contribute to this guide.
Revised 5 April, 1997