What is a grassland?

The most endangered terrestrial ecosystem is found right here in Canada. It is a different habitat than you might expect—and closer than you might think: temperate grasslands.

Impact Area

What is a grassland?

When you think of the world’s most endangered ecosystems, what comes to mind? At a quarter of their original size, Canada’s grasslands make the top of the list.

And yet, they are one of our most important ecosystems, acting as powerful carbon sinks, preventing soil erosion and providing critical habitat for pollinators.

Thriving in warm summers and cold winters, Canada’s temperate grasslands are made up mainly of grasses, sedges and wildflowers—with very few trees. The blooms provide essential food for pollinators. Some species you might find, depending on where you are, include prairie dogs, deer, coyotes and gazelles.

Grasslands are biodiversity hotspots that provide ecosystem services and help reduce the impact of climate change. The challenge is to conserve them while preserving Canada’s agricultural prosperity.

Where are the grasslands

In Canada, temperate grassland ecosystems are shaped by having less rainfall and a wide range of temperature.

These grasslands are found in abundance on the Great Plains, which stretch from the Gulf of Mexico through the United States to Prairie Canada. The Great Plains and, especially, the Prairie Pothole Region are the most important and threatened waterfowl habitats on the continent.

Prairie Pothole Region

The concentration of prairie habitats in Western Canada and south to the United States was once the centre of the largest expanse of grassland in the world. When glaciers receded 10,000 years ago, they left millions of depressions that are now wetlands, also known as prairie potholes. These potholes are rich in both plant and invertebrate life and are surrounded by a matrix of grassland habitats.

Southern Ontario

In southern Ontario, grassland is a vanishing ecosystem that once covered vast areas of Carolinian Canada and beyond. Today, just 1 per cent remains of historic prairie landscapes in Ontario. In past centuries, most grassland was converted to farmland to access the deep, productive soil. Because there is so little prairie left, endangered songbirds and more than 150 rare plants rely on the remaining habitat for their continued existence in Ontario.

Weston Family Prairie Grasslands Initiative: Helping farmers and ranchers enhance biodiversity on their land © DUC

How grasslands work

Grasslands and wetlands fit together in a beautiful mosaic. The ecosystems co-exist to provide complementary habitat for hundreds of wildlife species.

The three main factors that contribute to the formation of temperate grasslands are climate, grazing by large animals, and fire.

Climate – The amount and distribution of rainfall, combined with temperature, determine whether a grassland or forest can grow. Minimal rainfall means that trees cannot be supported, and grasses tend to dominate.

Fire – Grassland fire helps to reduce woody species (brush and trees) and dead plant matter, which lets sunlight reach the newly revealed grasses and flowers. Fire also activates the dormant seeds of grassland vegetation.

Grazing – Large animals such as bison and cattle help to stimulate plant growth in the grasslands. They graze on rapidly growing grasses, allowing a diversity of plants to grow in their wake. Their hooves aerate the soil and slice up vegetation, allowing it to decompose and regenerate more quickly. Their dung is a fertilizer for plants, spreading nutrients across the ecosystem and providing a place for hundreds of insects to lay their eggs. These insect populations are food sources for bird species in the grasslands.

The deep roots of grassland biodiversity

The unique biodiversity of plant species makes these ecosystems important for mitigating the effects of climate change. That’s because they take carbon out of the atmosphere and store it in their roots and soil. This is where up to 30 per cent of the world’s organic carbon is stored. They also hold soil in place, reducing erosion and floods.

Through photosynthesis, grassland plants draw carbon dioxide from the atmosphere into their stems, leaves and roots. Most of the carbon is stored underground so when fire moves through the grassland, the carbon can remain sequestered in the roots and soil. By comparison, forests mainly store carbon in leaves and woody biomass and when trees go up in flames, they release carbon back into the atmosphere.

The science of carbon storage

Collaborative study aims to demonstrate carbon-storing power of grasslands

Meet the people saving Canada’s native grasslands (The Narwhal)

One of the world’s most endangered ecosystems

What we do

Canada’s grasslands have rich soils that continue to make them attractive for growing food.

We’re working with landowners to reduce conversion of grasslands to cropland and increase grassland restoration. As a preferred sustainability partner, we’re working with agriculture associations and grassland landowners to conserve and restore legacy grassland ecosystems in Prairie Canada and beyond.