The pale green to cream colored bark of the quaking aspen is equally recognizable, and is to many, just as beautiful as the tree's leaves. The thin, smooth bark of young aspen trees is food for numerous wildlife species including deer, elk, beaver, and porcupine. As the trees age, the bark becomes thicker and more furrowed, with long flat-topped ridges of remaining smooth bark. Older bark is commonly dark brown or gray in color, and may, near the very base of the tree be almost black. Even the thickened bark of mature trees provides little insulation though, resulting in the aspen's inability to survive even small fires.