What is a Prairie?

Prairies are specific ecosystems that are part of the temperate grasslands, savannas and shrublands. They generally have moderate rainfall and a diverse array of grasses, herbs, and shrubs, rather than trees. The word “prairie” typically refers to the Great Plains of the United States. Prairies contain lush flowers and grasses and rich soil.

“Prairie” is the French word for “meadow.”

U.S. Prairie Map

Image Source: https://commons.wikimedia.org/wiki/File:United_States_Prairies.svg

Our Prairie Past

Formation

The North American prairie lands were formed by the uplift of the Rocky Mountains, creating a rain shadow that resulted in lower precipitation downwind. During the last glacial advance (about 110,000 years ago) and retreat (about 10,000 years ago) most of the material for the prairies was deposited and the terrain leveled.

The tallgrass prairie, one of the most biologically diverse ecosystems in the world, still blanketed our state and much of the Midwest up until just under 200 years ago. Expansive seas of grasses and wildflowers in a mosaic of colors and textures competed for nutrients, water, and sunlight…with some plants growing taller than a horse and rider. Not a single tree was recorded on original land survey maps in some Iowa counties.

This diverse ecosystem once covered 170 million acres of North America and 14 states in the Midwest, including more than 80% of Iowa.

Disturbances

The tallgrass prairie evolved over millennia to withstand (and require) periodic disturbances including fires and grazing. These disturbances suppressed tree encroachment and created a process for nutrients to be recycled back to the soil.

Grazing

For tens of thousands of years, native ungulates such as bison, elk and deer inhabited and shaped the prairie as a considerable portion of the biomass was consumed each year. Animals like bison, elk, deer, rabbits, and grasshoppers feasted on the prairie's diversity, stimulating growth, particularly for grasses. The tender growing points of prairie plants are an inch or so below the ground and thus not injured by fire or gnawing teeth.

Fire

Fire played an integral role in shaping the prairie and is fundamental to its continuation.

For 10,000-20,000 years, native people lived and subsisted in the prairie lands, using fire for hunting, transportation, and safety. As a natural part of the prairie ecosystem, fire cleared out dead plant material, killing trees but not prairie seeds.

Either set by lightning (about every 5 years) or by Native Americans; fire efficiently replaced nutrients to the soil while restricting tree growth. When fire is not present, trees encroach on the landscape and shade out the prairie plants.

Plants

The tallgrass prairie is tall! Indian grass, big bluestem, little bluestem and switchgrass all average between 5-6.5 feet, with occasional stalks reaching more than 9 feet. Interspersed was a huge diversity of forbs (flowering plants). Wild indigo, mountain mint, coneflowers, and black-eyed susans, dotting the meadows with blazing color and richness. Each flush of color in a season tended to reach taller than the previous blooming species.

Wildlife

This tapestry of plants and animals supported a wide community of insects, birds, mammals and more. These patterns existed in the prairie for thousands of years and have shaped the selection of plants and animals that have become uniquely adapted to these specific conditions.

North American Grassland Birds Report

Pollinators

Pollinators, like bees and butterflies, played an integral role in the Tallgrass prairie. By spreading pollen between plants, pollinators help the prairie species reproduce and thrive. Prairie flowers and grasses evolved over thousands of years with the insects and birds who pollinate them. Many species of butterfly can only lay their eggs on specific host plants, like the relationship between the monarch butterfly and milkweed.

Ecosystem Services

Tallgrass prairie plants sink their roots deep into the ground (up to 12 feet), providing a strong anchor for the plant, as well as access to moisture in dry times. Despite periodic droughts and floods, the Tallgrass prairie ecosystem suffered little soil erosion and the decomposition of root and plant material created Iowa's legendary black soil.

Cultural Relevance

Indigenous Peoples and Bison

The archeological record shows nomadic hunting of megafauna as the main human activity on the prairie for thousands of years. Native peoples would drive bison into fenced pens or off cliffs. The subsequent introduction of the gun, increasing efficiency and killing power, coupled with the indiscriminate killing of megafauna by European settlers lead to the decimation of the bison population. Astonishingly, the bison population plummeted from millions to just a few hundred in about 100 years.

The Great American Desert

When the first settlers arrived at the tallgrass prairie they called it the “The Great American Desert." Even though the tallgrass prairie had survived and thrived for thousands of years, much of it was lost within 1-2 generations during westward expansion. Nearly all of it disappeared between 1830 and 1900 when Iowa was settled. Marshes and prairie potholes were drained and agricultural development proceeded along the major waterways.

Historical reports describe the sound of the plow slicing through the strong roots of the prairie (invented by Illinois blacksmith, John Deere) sounding like pistol shots. The confined grazing pattern of European cattle and the loss of nitrogen adding animals like bison hastened the prairie's decimation. Today less than 0.1% of the original tallgrass prairie remains in Iowa.

States once covered in a sea of biological diversity are now referred to as the Corn Belt for their highly productive soils and monocultures.