Martin Mittelstaedt
November 24, 2008

When it comes to setting aside land for parks and nature reserves, the big question is how much is enough?

For years, countries have been urged to earmark about 10 per cent to 12 per cent of their land in protected areas, but now some scientists are saying this widely accepted figure might be woefully inadequate.

The new view - for which Canada's extensive boreal forest is becoming an international test case - is that at least half of an entire ecosystem needs to be preserved to give it a decent chance to remain a fully functioning natural environment.

If you preserve 10 per cent of habitat "and let the rest go, you are squarely in the middle of mass extinction territory," contends Jeremy Kerr, a professor specializing in conservation biology at the University of Ottawa.

Prof. Kerr is among a number of scientists in both Canada and abroad who have been arguing that far larger areas are needed for conservation lands. They're trying to have the preservation of half the boreal forest in Canada's north be a model for other globally significant areas, such as the Brazilian rain forest.

The conservation target of around 10 per cent arose in the 1980s, when many governments set their first national biodiversity goals. The idea was that putting aside about a tenth of a country's total land area in parks or nature reserves would be enough to forestall species extinctions.

Canada used this approach in 1992, when the provinces and the federal government agreed to preserve small, representative parcels of land in each of the country's approximately 500 distinct ecological regions. At the time, environmentalists said meeting the goal would require putting about 12 per cent of the country in nature reserves.

But researchers now contend that numbers around 10 per cent, the amount now off limits to development in Canada's boreal forest, never had a valid scientific foundation. A study published in 2005, by researchers at the University of Idaho, reviewed all the conservation literature from the 1970s and 1980s, and couldn't find any scientific reasons for selecting the number. The study, in the journal Bioscience, concluded the figure was "arbitrary" and "without evidence of biological substance or conservation merit."

Other research is indicating that far more land than anyone might have though possible may be needed to fully protect areas and their endangered species. One U.S. estimate found that if the ecosystem around Yellowstone Park were to offer complete protection for highly imperilled species, about 70 per cent of the land base would need to be preserved, compared with 27 per cent currently.

"Everybody thought Yellowstone was a fantastic place. It's big, big enough. It can conserve everything, but buffalo don't stay there, wolves don't stay there," says Terry Root, a senior fellow at California's Stanford University Center for Environmental Science and Policy.

Prof. Root is among a group of 14 prominent scientists from the United States and Canada who've recently set up an advisory panel to lobby Canadian governments to accept the 50-per-cent target for the boreal forest, considered the largest remaining relatively untouched wilderness in the world. Others include University of Victoria climate-change expert Andrew Weaver and Canada's top aquatic biologist, University of Alberta professor David Schindler.

A boreal forest similar to the one in Canada also exists in Russia, but the group isn't lobbying for preservation there because of the lack of respect for the rule of law in that country and its wild west development mentality.

The scientists say their estimate of having 50 per cent set aside is based on computer modelling that indicates it is the amount of land needed to maintain species across a landscape.