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Grasslands
Prairie Restoration
Restoring a prairie may occur in two ways: (1)
rehabilitating a degraded site, or (2) reestablishing a site by
planting a new prairie. Before any management techniques can begin,
it is important to determine if the site was historically a prairie
and to identify any prairie plants still growing. This chapter will
guide you through the step-by-step process needed to restore your
prairie.
Landscape
Perspective
Before settlement, grasslands were
mainly barrens, savannas, and wet prairies with a few dry prairies.
Dry prairies, in particular, disappeared quickly because they often
grew on rich soil and were easy to clear for farming. Researchers
have identified at least 39 prairie areas that existed prior to
European settlement. They ranged in size from 80 acres to 25 square
miles.
Prairies were grasslands, which had few
if any trees. Barrens, on the other hand, may have had several
trees scattered across each acre of their landscape. Savannas, which served
as transition areas between grasslands and forests, had many trees per acre
but not more than 50 percent canopy cover. Grassland specialists
classify most savannas as either oak savannas or
jack pine savannas.
Prairie-forest continuum: Boundaries are
not clearly established, blending occurs between habitat
types. |
The Importance of
Prairies
Prairies are an important part of any
ecosystem where they occur. They provide
key habitat for many species of wildlife, serving as important
breeding, feeding, nesting, and brood-rearing centers. Bobwhite quail, wild turkeys, bluebirds, meadowlarks, bobolinks, and
other songbirds eat the abundant insects and
seeds that prairies provide. Mice, voles, shrews, and woodchucks,
along with many kinds of ground-nesting birds, raise their young
there.
Prairie plants encourage infiltration of water into the soil
because their root systems are deep. Better percolation increases
recharge of ground water. Besides making better use of water, they
are very efficient at removing nutrients such as nitrogen, phosphorus, and
potassium from the soil. These long-lived plants can tolerate
seasonal flooding, drought, and other severe environmental
events.
Prairies often become established in areas where flooding, fire,
or other disturbance limits competition from trees and shrubs. Wet
prairies, for example, may be under water part of the year; dry
prairies may grow in sandy soils too dry for trees and shrubs.
Fires, whether occurring naturally or lit deliberately by Native
Americans, played a dominant role in the ecosystem because they
encouraged native grasses and wildflowers) to grow and discouraged the
encroachment of trees and shrubs.
Prairie
Identification
One of the first steps to determine whether or not you have a
remnant prairie is to check historical maps showing the
presettlement vegetation for your county. Your local Conservation District office has these
maps, which show the forests,
prairies, and wetland types.
The best way to identify prairie
grasses and wildflowers is to carry a field guide containing color
photos or drawings. Major grasses to look for include big bluestem,
little bluestem, Indiangrass, and switchgrass. Key wildflowers are
rough blazing star, gray-headed coneflower, common evening primrose,
butterflyweed, black-eyed Susan, moth mullein, swamp milkweed,
cardinal flower, Joe-pye-weed, hoary puccoon, aster, coreopsis, tick
clover, bee balm, prickly pear cactus, horse-mint,
and round-headed bush clover. You may find these plants
as scattered clumps across a grassland or opening, or you may discover them
as bunches in several smaller areas. Living treasures, these remnant prairies are
a snapshot to past native systems, and every attempt should be made
to restore them.
For species descriptions, refer to the chapter on Warm Season
Grasses in this section and to the Wildflowers
chapter in the Backyard Management section.
Prairies may be stable grassland systems where the invasion of
trees and shrubs does not occur. However, more commonly, there is
encroachment of oak, pin cherry, spirea, sumac, aspen, autumn olive,
june berry, sassafras, and white and jack pine.
Evaluating the Restoration
Process
The Wetland section covers restoration and management of wet meadows,
fens, and wet prairies. This chapter
focuses on the restoration of dry prairies, barrens, and savannas.
The three key methods of restoring them include the following:
- Tree and shrub reduction or
removal
- Prescribed burning, which may be
followed with interseeding of prairie plants
- The new planting of the
site
For best results, choose the method that produces the greatest
benefit with the least amount of disturbance to the ecosystem.
Remember that in most prairie restorations, you are dealing with a
sick patient. The way to health is to nurture the patient over
time.
The way to do that is to first identify your goal. If you want to
restore an oak savanna or barren, for example, then allowing limited
tree growth on the site is acceptable. But if the goal is to restore
a tallgrass prairie, then trees must be eliminated and kept out. If
remnant prairie plants simply do not exist, you may have to start
over completely.
Tree and Shrub
Removal
Sumac, aspen,
black locust, autumn olive, hawthorn, honeysuckle, buckthorn, and
raspberry are aggressive species that often take over native prairies.
If any of these aggressive species exist on your restoration site,
remove them by cutting them between July through September and
immediately applying a glyphosate herbicide such as Roundup to the stump. Be
sure to follow all label directions.
On sites with high densities of oak, hickory, or black walnut,
you will need to remove or greatly reduce their numbers. Left
unchecked, such species increase to the point where they shade the
ground and will not let grasses and wildflowers grow. Use a chainsaw
on larger trees or a limblopper on those that are sapling size.
Another method to kill them is to cut a two-inch deep band around
the trunk at two feet above the ground and another two inches
higher. To complete this "girdling" treatment, use an ax or hatchet
to remove the bark between the two cuts.
Prescribed Burning and
Interseeding
On sites where many prairie plants currently exist and there is
limited competition from trees and shrubs, a prescribed burn is in
order. Fire increases prairie plant growth, flowering, and
reproduction and lengthens their growing season, while reducing the
growing season for weeds. Further, fire helps control invasion by
killing woody plants and returning important nutrients to the
soil.
A prescribed burn is a planned fire that is burning for a
specific purpose. First, create a burn plan, which includes
discussion with local authorities, obtaining any required permits,
and observing all restrictions and safety procedures. These include
carrying out the burn on a day with light wind and relatively low
humidity in early spring or late fall when vegetation is dry. For
more information, see the chapter on Prescribed
Burning within this section.
For remnant prairies that have low plant densities or lack a
variety of prairie plants, consider interseeding after the
prescribed burn. Interseeding is the process of sowing seed into the
existing soil. Hand broadcasting, machine broadcasting, or drilling
with a no-till planter are interseeding methods. When broadcasting
by hand or machine, prepare a mixture of 50 percent seed and 50
percent perlite, vermiculite, or cracked oats. The material
will help carry the light, small seeds and enable you to spread them
at recommended rates. Divide the site into sections to ensure that
you will have enough seed to cover it uniformly.
Try to match the seed mix to the soil type, using plants that
like moist conditions or sites in low-lying areas and plants that
prefer dry soils on upland sites. For best results, secure
local seeds, collecting from on site or as close to the site as
possible. You should always check with landowners for permission.
After broadcasting the seed, incorporate it into the soil by shallow
(less than 1/2 inch) hand-raking, dragging, disking, or by the
pressure of a cultipacker. For sites larger than three
acres, a no-till drill is the best way to get the
seeds into the ground.
Planting
In highly degraded areas, such as former agriculture fields,
where very limited or no prairie plants exist, burning will not be
enough to ensure a quality restoration. Planting a new prairie may
be the best management practice. Consider two methods:
- The use of conventional farm
tillage to prepare the site by killing or removing all former
vegetation before planting.
- The use of chemicals to eliminate
all present vegetation, and a no-till drill to incorporate the
seed into the soil
.
With either method, plant during the period May 1 to June 15.
Native grasses and wildflowers need only be planted 1/4 inch to 1/2
inch below the soil. However, it is not uncommon to see seed sitting
on top of the surface after planting. For more information, see the
chapter on Grass Planting
in this section.
Post-Planting
Maintenance
The amount of weed seed present in the planting site is usually
the most variable and unpredictable factor in prairie restoration.
There is no way to predict with certainty the amount of weed
competition that will be present during the first few years of
restoration. Landowners can do four things to reduce the weed
problem:
- Plant as late as possible in
spring,
- Mow or hand weed to reduce
shading
- Burn at prescribed times
- Spot apply herbicides
- Have lots of
patience
Give the site at least three full years because the clump-growing
native grasses require that long to establish themselves. After the
first growing season, it is not uncommon to have only one plant per
square yard. The grass may only be six to eight inches tall
during its first year of growth and difficult to recognize until it
grows a seed head in late summer of year two. After the second
growing season, each plant may be one to two feet tall and occupy a
square foot or so. By the end of the third growing season, you
should have an established stand of native grass three feet or
taller, depending on the species planted.
In summary, restoring a prairie is exacting, time-consuming labor
that requires patience. Once established, however, prairies will
need only periodic maintenance. Not only are they a key type of
habitat for many birds and small mammals, but they offer pleasing diversity to the landscape. Native prairies
with their ever-changing kaleidoscope of wildflower color are a
delight to observe. In winter, the copper color of standing bluestem
provides beauty to a stark landscape while affording protective
cover for many kinds of wildlife.
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