A prairie is an open landscape containing an ecological community where the vegetation is made up of native grasses and wildflowers. Mature trees, which are predominately oaks, provide less than 10% canopy cover (Raven, 1986). Grasses such as Big Bluestem, Indian Grass, and Prairie Cord Grass can grow to such heights that early explorers reportedly found themselves lost on horseback in the tall grasses. Nestled among these grasses is an impressive diversity of wildflowers, which are also called forbs.

A prairie is not simply a mix of flowers and grasses. A healthy prairie is full of the humming, buzzing, and singing of the many animals who live there. Numerous species make use of the rich habitat, it would be a major task to list them all. Of these, some of the most interesting mammals include: meadow vole, common shrew, long-tailed weasel, American badger, red fox, and the eastern cotton tail rabbit. Birds such as the bobolink, eastern meadowlark, and savannah sparrow also depend on these areas for food and shelter. An amazing range of reptiles have adapted to this habitat. However, by far the most numerous prairie animal species are the invertebrates, including butterflies, grasshoppers, dragonflies, ants, beetles, and spiders.

A prairie community is established as a result of a mirco-climatic system that favours grasslands over forest. Tallgrass prairies are established on slightly more moist soils when compared to the short grass prairies. Between these two prairie systems a mixed grass prairie is sometimes found , whose plants are neither tall nor short. Each of these types of prairies is a distinct mix of grasses and wildflowers.

In terms of biomass, tallgrass prairies exist ‘upside-down' with 65% of the prairie biomass existing below ground in their massive root systems. Tallgrasses can grow to heights of 2 metres, and their roots can grow up to 4 metres deep. (Pull Quote) Because of their extensive root systems, these plants are conservers of water and nutrients, making them very drought tolerant. This also leads to the prairies seeming rather nutrient poor, even though once they are cleared they provide rich farming soils. These extensive root systems also prevents shallowly-rooted non-prairie species from invading. Such deep root systems break down the soil column and add large amounts of organic matter, creating deep, nitrogen rich (agricultural) soils. Soils like these support the ‘bread-basket' regions, the intense concentration of organic nutrients create an incredibly fertile area. This soil formation is fundamental to understanding why so few remnants of prairie still exist in Ontario; when Europeans came they settled the open and easiest land first, ie. the open, nutrient rich prairies.

Another defining quality of the tallgrass ecosystem is the necessity of periodic fires to burn the landscape. Historically, fire was set both by lightening strikes and by Aboriginal peoples (Delaney, 1999). Fire regenerates prairie by suppressing non-prairie plants, clearing dead plant material and creating a nutrient balance in favour of the prairie system as the fire volatilizes nitrogen. After a burn the blackened soil attracts sunlight which warms the soil favouring the heat loving prairie plants. Without fire, conditions change to favour non-prairie species. Lack of fire is one of the main reasons why many of Ontario's remaining prairies are overrun with non-prairie plants, including woody plants which will eventually shade and kill the prairie grassland beneath them. Two other reasons leading to the decline of the tallgrass prairies are the occurrence of invasive exotic plants, mostly of European origin, and the high levels of unnatural nitrous oxide pollution in the region. Such nitrogen rich soils tend to favour early successional, nutrient loving plants. Oddly enough, prairie plants like less nitrogen in their soil, they hold most of it in their root systems. However this gets released again as the prairie is converted to agricultural uses, leaving behind the legacy of a very nitrogen rich soil.

Non-prairie species may be reduced by grazing, as they are not well adapted to this, their roots are too shallow. Ontario's prairies were historically grazed by elk, not the bison of the west. Today, white-tailed deer are the largest browsers, groundhogs and rabbits are the largest grazers. However, all herbivores (plant eating animals) are important ranging from large mammals to grasshoppers and locusts. In comparison, one of the largest human threats on prairie ecosystems is the overgrazing by our commercial livestock.