Gravel-bed rivers and their floodplains are the lifeblood of ecosystems and need to be allowed to run and flood unimpeded if species are to be protected and communities are to cope with climate change, a ground-breaking scientific study has found.

The broad valleys formed by rivers flowing from glaciated mountains, such as those found throughout B.C. and Alberta, are some of the most ecologically important habitats in North America, according to the team of scientists who have done the first extensive study of the full range of species that rely on gravel-bed rivers, ranging from microbes to bears. The paper was published online Friday in Science Advances.

In the region that stretches from Yellowstone National Park in Wyoming to the northern Yukon, gravel-bed river flood plains support more than half the plant life. About 70 per cent of the area’s bird species use the floodplain, while deer, elk, caribou, wolves and grizzly bears use the plains for food, habitat and as important migration corridors.

While everyone knows that fish rely on rivers, the scientists found that species such as cottonwood trees need the river flood to reproduce and the ever-changing landscape of changing channels and shifting gravel and rocks supports a complex food web.

Gravel-bed rivers are much more than water flowing through the channel, said lead author Ric Hauer, director of the University of Montana’s Center for Integrated research on the Environment.

“The river flows over and through the entire floodplain system, from valley wall to valley wall, and supports an extraordinary diversity of life. The river is so much bigger than it appears to be at first glance,” he said.

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