Register for an account


Enter your name and email address below.

Your email address is used to log in and will not be shared or sold. Read our privacy policy.


Website access code

Enter your access code into the form field below.

If you are a Zinio, Nook, Kindle, Apple, or Google Play subscriber, you can enter your website access code to gain subscriber access. Your website access code is located in the upper right corner of the Table of Contents page of your digital edition.

Planet Earth

The Bear Necessities

By Josie GlausiuszDecember 1, 2000 6:00 AM


Sign up for our email newsletter for the latest science news

Grizzlies in the Pacific Northwest cannot thrive without a forest home. Oddly enough, the reverse may also be true. "People think of bears as just big, replaceable feeders in the food chain, that they don't have any particular effect on the forest," says Barrie Gilbert, an ecologist at Utah State University. "But it turns out that bears are in fact very important." Gilbert and his colleague Arthur Morris ventured into the woods bordering the Koeye River in British Columbia and discovered that grizzly scat and surrounding soil samples contained high concentrations of a heavy isotope of nitrogen commonly found in salmon flesh. The fish absorb the nitrogen in the ocean before traveling upstream into the forests to spawn. Gilbert and Morris believe the bears gorge themselves on salmon and bring the nitrogen into the woods by defecating, urinating, or carrying half-eaten carcasses. The nitrogen is a potent fertilizer. Jim Helfield of the University of Washington in Seattle found that trees close to salmon-filled rivers in Alaska grow three times as fast as those near rivers that do not contain significant numbers of the fish.

3 Free Articles Left

Want it all? Get unlimited access when you subscribe.


Already a subscriber? Register or Log In

Want unlimited access?

Subscribe today and save 70%


Already a subscriber? Register or Log In