Rich silt-loam soils provide prairie ecosystems with a superior nutrition base, which contributed ironically, to its loss. Tallgrass prairie soils proved ideal for agriculture. Corn and soybean crops occupy lands once covered in prairie grasses and forbs.
Many wildlife species depend upon these habitats. With the loss of the prairie, species such as the upland sandpiper have declined rapidly. Habitat fragmentation also plays a role.
Some wildlife species are classified as area sensitive, meaning that they require a large habitat base from which to fill their ecological needs. Some species remain threatened even in areas where tracts of prairie habitat exist.
Prairie Habitat Disturbance
Habitat disturbance is the primary cause of prairie decline. Disturbance can have natural and man-made sources. Prairies evolved with fire. In fact, controlled burning is an effective restoration tool for resources managers. Fire suppression causes habitat degradation.
Other disturbances occurred with the introduction of non-native species. Cool-season grasses such as Kentucky bluegrass and tall fescue are opportunistic, aggressive species which can easily out-compete native plants for resources.
Native species also present threats. Canada goldenrod is a native prairie species. However, it can become invasive and weedy, converting a biologically-diverse prairie to a monoculture. Such an ecosystem provides little value to wildlife.
Prairie Restoration Techniques
Prairie restoration first requires the identification of a threat. As long as the threat exists, the prairie is at risk. An initial plant inventory provides a baseline for restoration efforts. Identification of the species present as well as their density gives a picture of the ecosystem’s overall ecological health.
Control measures vary with the type of threat. Some plants such as garlic mustard are easily hand pulled. This control method works best when done before the weeds have gone into flower to prevent seed dispersal.
Girdling can control woody species that have invaded a prairie. Girdling interferes with the distribution of nutrition through the tree, eventually killing it. Shrubs and trees often encroach into prairies because of fire suppression. Fires maintain prairies at a certain stage in habitat succession.
Controlled Burning in Prairie Management
Fire has always been a part of prairie existence. Most fires are caused by lightning. Native Americans and European settlers also used fire for hunting and habitat management. Fire provides several benefits to a prairie.
It removes the litter accumulation. If litter accumulates, it alters the soil temperature by preventing sunlight from reaching the ground. Plants may not be able to germinate if minimal ground temperatures are not met. Likewise, it can impact low temperatures needed for vernalization.
Prescribed burns work best for large tracts of land. Spring burning destroys cool-season grasses and prevents re-infestation by killing seed stock. Fire controls invasive tree species by damaging foliage, often to the point where the plant cannot recover.
Warm season grasses, on the other hand, are favored by spring fires. The litter layer is removed, restoring soil temperatures. Nitrogen and other nutrients are made available to germinating plants.
Restoration of prairie ecosystems provides habitat for many wildlife species, including waterfowl populations which will use prairie potholes for nesting and migration habitat.
For people, prairies are equally important. Prairies provide erosion and non-point source pollution control. They protect ground and surface water as well as act as buffers for wetlands. Prairie restoration is essential for an ecologically-sound planet.
Sources:
U.S. Army Corps of Engineers: “Status and Importance of Prairie Ecosystems” el.erdc.usace.army.mil
Ducks Unlimited: “Prairie Pothole Region” ducks.org
