In struggling to save endangered ecosystems, America frequently overlooks one of its most valuable resources, according to one expert. That resource is beaver.

"Our argument is that the restoration target for streams with forested riparian zones has got to acknowledge the diversity brought to river systems by active beaver populations," says Professor Melinda Daniels. She and her colleagues have recently carried out extensive research into the effects of beaver on thickly wooded streams. The research was led by Professor Denise Burchsted.

According to Burchsted, Daniels and the other experts, long ago there was beaver as far as the eye could see in North America: but then the hunters came, hungry for pelt. There was a terrible beaver scarcity in the early 19th century, but since then, apparently, beaver have "rebounded". The treetrunk-gobbling varmints are apparently invaluable when it comes to sorting out rivers messed up by meddling humans.

"We can restore rivers in a way that mimics the naturally diverse beaver streams, and we can save a lot of money in the process," argues Daniels. She and her colleagues suggest that beavers will often act as unpaid maintenance crews. In many cases if an old dam breaks and forms a gap, beavers may build their own dam to patch the gap and recreate the ecosystem that previously existed.

Burchsted, Daniels et al's new paper The River Discontinuum: Applying Beaver Modifications to Baseline Conditions for Restoration of Forested Headwaters can be read here by subscribers to the journal BioScience. ®