By Derek Leschasin, Digital Journal, January 24, 2010
The "Sea of Grass" which greeted European explorers when they ventured into the heart of North America was long ago reduced to a fraction of its original extent. But a new study shows that what remains in Canada is shrinking fast.

The tall-grass prairie is a unique eco-system comprised of minimal tree and shrub growth, and dominated by species of grass, such as Big Bluestem, which can grow to shoulder-height. When Europeans arrived in North America, bison roamed it in huge herds, and many other species were adapted to the conditions as well: plants, birds, and other mammals. Native American tribes learned to live off this environment.

Canada once boasted over 6000 square kilometres of tall-grass prairie. According to the Canadian Press, a study published by a University of Manitoba ecologist is reporting that of the less-than-one per cent remaining of that expanse, much is disappearing, and quickly. More than one third of prairie identified in 1980s surveys, mostly in Manitoba, is now gone.

"Even though we knew that it was extraordinarily endangered in the late 1980s and took steps to try to conserve it, in fact, in general the ecosystem has declined even further from this previously seriously endangered state," Nicola Koper, the study's author, told the Canadian Press. "Most of it has been heavily impacted by humans and is getting worse."

Most of the Canadian and American prairies were plowed under by European settlers, due to the extremely fertile soil. The movement of herds of bison and wildfire activity traditionally held back tree growth and invasive species, but with those factors largely gone, remaining prairie is slowly reverting to forest and parkland.

Environmentalists and government are attempting to protect what remains. A relatively large area of tall-grass prairie exists in southeastern Manitoba, under the stewardship of environmental groups and the Nature Conservancy of Canada.

Conditions that existed before European settlement are recreated through activities such as controlled burns and limited grazing.

"Where remnant prairie exists, if it isn't being managed as a prairie, it's being largely invaded by invasive species," said Cary Hamel, a Nature Conservancy employee. "We've kind of drawn a circle around a part of Manitoba... At that one location, I feel pretty good that it's a case where we can preserve it into the future."