Prairie restoration is a way to help fix prairie lands that were damaged because of things like farming, building homes, or other human activities. The main goal is to bring these areas and their ecosystems back to how they looked before they were harmed.
In the United States, after the Black Hawk War ended in the mid-1830s, people from northern Europe and the northeastern part of the U.S. moved into the prairie regions. These settlers cleared the tall grasses and wildflowers to grow crops like soybeans and corn. By 1849, most of the prairie grass species had disappeared to make space for farming. Today, restored prairies and the few remaining grasses are only a small part of the once-large prairie that covered much of North America, from western Ohio to the Rocky Mountains and from southern Canada to Texas. For example, the state of Illinois once had over 35,000 square miles of prairie land, but now only about 3 square miles of the original prairie remains. Over-farming, drought, and the lack of grasses to hold the soil together caused the Dust Bowls of the 1930s.
Problems like soil erosion and fewer types of plants and animals have happened in areas where prairie grasses used to live. To fix this, in Europe, people often use methods like letting nature regrow plants on its own, planting mixtures of seeds, moving plants from other areas, and removing and moving topsoil. Keeping tall grasses healthy often involves using controlled fires, which help grasses grow stronger and return nutrients to the soil.
Even though restoration cannot fully bring back all the original variety of plants and animals, these efforts help natural ecosystems recover. This is helped even more by bringing back important living things from the original plants’ environment. Prairie soil is also very good at storing carbon. As carbon sinks, prairie soil helps reduce the amount of carbon in the air through a process called carbon sequestration. This stored carbon supports the survival of many different plants and animals in the prairie ecosystem.
Purpose
Erosion happens when forces on the Earth's surface wear away the material in the Earth's crust. In areas where prairie grasses once grew, the loss of the deep, fibrous root systems of tallgrass plants left soil exposed and loose. Ecologically, restoring prairies helps protect the Earth's topsoil, which can be damaged by wind and rain (especially heavy rains caused by climate change) when prairies are turned into farmland for crops like corn, barley, and wheat. Over time, erosion weakens the soil's ability to support plant growth and farming.
Prairie restoration brings back the deep root systems of prairie plants, which help hold soil together and reduce erosion by allowing water to filter through the ground more effectively.
Prairie soil also helps store carbon. Carbon dioxide is a gas that traps heat in the atmosphere, and about 40% of it comes from human activities, making global warming worse. Prairie grasses take carbon from the air through photosynthesis and store it in the soil. When prairies are not disturbed, the soil acts as a carbon sink, absorbing more carbon than it releases.
Many prairie plants are strong and can survive droughts, extreme temperatures, diseases, and native insect pests. They are often used in xeriscaping projects in dry areas of the American West. On a larger scale, communities and businesses are creating restored prairie areas that store carbon in the soil and support the biodiversity of over 3,000 species that rely on grasslands for food and shelter. Research in Walnut Creek, Iowa, shows that converting farmland back to prairies improved groundwater quality over 10 years. Changing the types of plants grown can reduce groundwater contamination from chemicals and help address water security issues.
Prairie restoration can happen on large or small scales. Small backyard prairies, called micro-prairies, can improve soil health, reduce erosion, and absorb excess rainwater. Micro-prairies are small habitats, usually less than one acre, located in urban or developed areas. These small prairies provide homes for native plants and animals, including pollinators like butterflies, which rely on specific plants for food. They also offer nesting sites for pollinators, such as hollow stems or bee boxes, and protect pollinators from habitat loss and pesticides.
Micro-prairie plants also help store carbon, improve water quality by filtering pollutants, and change soil composition. Their deep roots store carbon in the soil, and their high growth rate captures carbon quickly. Prairie plants grow well in poor soil, help move nutrients through the soil, and improve soil fertility. Their large leaves trap airborne pollutants like dust and pollen, and the microorganisms in prairie soil break down harmful substances. Prairie plants can also absorb pollutants like heavy metals and excess nutrients from water and soil.
Micro-prairies generally help local ecosystems and biodiversity. However, some studies show risks if not managed properly. For example, introducing non-native plants can harm native species, and overgrown prairies may increase fire risks. Regular mowing or burning can reduce these risks. Standing water in prairies may attract mosquitoes, but proper design and maintenance can prevent stagnant water.
In cities, permaculture is a good method for creating micro-prairies. Permaculture uses natural systems to design sustainable environments. It encourages plant and animal diversity, mimics natural ecosystems, and uses companion planting to help plants grow together. Micro-prairies also teach people about prairie ecosystems and the importance of protecting native habitats.
Types of plants
Some common tallgrass prairie grasses are big bluestem, indiangrass, and switchgrass. Midgrass and shortgrass species include little bluestem, side oats grama, and buffalograss. Many prairie forbs, which are non-grass flowering plants, have special structures that help them survive when eaten by animals like American bison. Some forbs have hairy leaves that may help protect against cold and reduce water loss. Many forbs also contain special chemicals that were discovered by indigenous peoples and are still used today.
Early prairie restoration projects mainly used a few types of grasses and paid little attention to where the seeds came from. Over time, restorers learned that using a variety of plant species and seeds from local areas was more effective for rebuilding prairies.
Planting and aftercare of prairie plants
In Europe, when restoring land that was once used for farming back to prairie grasses, the most common methods include: natural regrowth, planting seed mixtures, moving plants from one place to another, and removing and moving topsoil. Natural regrowth works well when results are not needed quickly and when there are plenty of seeds or plants already present. Planting seed mixtures can be simple or complex, depending on how many different types of seeds are used. Simple mixtures are useful for covering large areas quickly. Complex mixtures, which are more expensive and take more time to grow, are used for smaller areas. Combining large areas with simple mixtures and small areas with complex mixtures helps create healthy spots that allow nearby areas to naturally recover over time. This supports ongoing natural restoration.
Fire is an important part of grassland health, whether the area is large or small, because grasslands depend on fire to survive. Controlled burns, which require a permit, are suggested every 4–8 years (after two growing seasons) to remove dead plants, stop other plants like trees from growing too much, and return nutrients to the soil to help new plants grow. A more wildlife-friendly option is to burn 1/4 to 1/8 of an area each year. This keeps homes for animals while still achieving the goal of burning. Native Americans may have also used fire to control pests like ticks. These planned burns encourage grasses to grow taller, produce more seeds, and flower more. If burning is not possible, mowing in sections over time is recommended as an alternative.
A newer method is holistic management, which uses livestock, such as cattle, to act like key species like bison. Some areas have bison, which helps protect the species. This method uses animals to do the work of mowing, which mimics natural processes more closely. Holistic management can also use fire, but only in limited ways and along with the mowing done by animals. In parts of Central Asia, human activities like grazing greatly influence how grasses grow.
In 1990, in South Africa, de Lange and Boucher found that smoke can help prairie grass seeds begin to grow. This method was shown to help seeds that were not growing start to sprout. Since then, this technique has been used in South Africa, parts of Australia, and North America.
Prairie contributors
Some well-known prairie restoration projects have been completed and kept up by government agencies, such as Midewin National Tallgrass Prairie, which is located in Wilmington, Illinois. This project is managed by the U.S. Department of Agriculture, Forest Service, and the Illinois Department of Natural Resources. It is built on part of the Joliet Army Ammunition Plant, specifically on land that was once polluted by TNT production. Since 1997, the project has made about 15,000 acres (61 km²) of restored prairie available to the public.
Another large restoration project is located at Fermilab, a U.S. government laboratory that studies atoms and is based in Batavia, Illinois. Fermilab covers 6,800 acres (28 km²) of land that was once farmland. The prairie restoration project covers about 1,000 acres (4.0 km²) of this area. This project started in 1975 and continues today with the help of Fermilab workers, teachers, botanists, and community volunteers.