Photo of the Day 154

Bison Herd, Yellowstone National Park, Wyoming, 1996

Photograph by Raymond Gehman

Bison thrive in Wyoming's Yellowstone National Park years after fires swept through more than a third of the park. Ecologists now regard wildfires as natural and beneficial in forest ecosystems. They return nutrients to the soil by burning dead or decaying matter, burn off disease-ridden plants and insects, and clear thick canopies and undergrowth, allowing a new generation of seedlings to grow.

(Photo shot on assignment for, but not published in, "Essential Element of Fire," September 1996, National Geographic magazine)