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Our Native Prairies - A Story of Grass

A profile pic of MaryMy interest in native plants is evolving into an interest in native ecosystems.  A native, and unique to North America, ecosystem is the prairie or what we call The Great Plains.  The North American prairie lies roughly between the Illinois and Missouri Rivers to the east and the Rocky Mountains to the west.  Though I find prairie plants quite interesting and beautiful, they are not the sorts of plants you usually find in your local nursery. You will most likely see native prairie plants in a roadside ditch or along a fence line.

What fascinates me about native prairie plants is what I don’t see.  Prairie plants have a ‘root-to-shoot ratio’ of two-to-one, meaning that two thirds of a prairie plant’s height is below ground so we see only a small portion of the prairie. So most of the prairie lies underground.   Young plants that show only an inch of growth above ground have spent most of their energy developing a root system a foot or more downward. Roots several feet deep tap moisture in times of drought.   Since grass grows from below, like human hair, rather that from its ends, like trees, prairie plants can survive weather extremes, mowing, grazing, and fire.  And these deep roots give The Great Plains its incredibly fertile soil for farming and sturdy grasses for grazing animals.

As you move from east to west, the rainfall decreases creating three different types of prairies.

Hayden Valley in Yellowstone National Park

Tall Grass Prairie

Tall grass prairie, forming the eastern portion of The Great Plains, receives up to 21 inches of rain per and is known as the true prairie.  Tall grass prairie is so-named because the component grasses - big bluestem, Indian grass and switchgrass - can reach 8 to 9 feet tall with root systems growing 9 to 12 feet deep. The entire state of Iowa was once tall grass prairie. 
 Tall grass prairie stays grassland because tree seeds cannot take hold in the soil, which is a dense mat of roots, rhizomes, bulbs, and rootstock. As these root systems break down, they add large quantities of organic matter to the soil creating very fertile farmland.

Early settlers had a hard time working this very dense soil with their wooden plows.   In 1837, John Deere, an Illinois blacksmith, developed a steel plow that was able to cut the prairie plant roots, thus making the soil ready for farming.  This fertile soil became one of America's most important resources.

Short Grass Prairie 

Short grass prairie borders the Rocky Mountains and consists of foot-high bunch grasses that have shallow root systems, need little water, and grow in heavy, clay soil.  This region receives an average of 10 to 12 inches of rainfall per year.  Short grass prairie is not well suited to agriculture and is used today as cattle rangeland.  Pronghorn, elk, and mule deer also graze on short-grass prairies. An example of a short grass prairie is the landscape you see when you drive I-90 between the Colorado state border and Denver.

Mixed Grass Prairie 

Nestled between the tall grass prairie to the east and the short grass prairie to the west, the mixed-grass prairies form a transition zone where tall grass and short grass prairies intermingle. Mixed-grass prairie supports grasses ranging from 12 inches to 48 inches tall. This is the land of the cattle empire of the mid-19th century and later the homestead soddies. The Badlands National Park protects a large expanse of mixed-grass prairie. Most of the region is covered by loess, which is wind-blown silt. The deep loess soils are fertile, but moderate precipitation and high evaporation rates limit vegetation growth. 

This is only the beginning of my story about our native prairie.  I still want to talk about prairie wildlife and flowers and how we can use this amazing natural resource.  So until next week, see if you can catch a glimpse of a prairie growing in your neighborhood or during your travels.