The relative absence of life on the forest floor begins in the soil. Pines create acid soil conditions which do not promote bacterial growth. Decay, therefore, carried on primarily by fungi, takes place very slowly. The result is the thick accumulation of discarded needles and branches, the resinous, sweet-smelling “duff.” Not far upslope from the trail a porcupine scuttles toward a stand of young pines. It moves slowly and silently, its quills making it look prehistoric. Again I am struck by the apparent changelessness of the pine forest. But looking around, I find everywhere signs that indicate change and struggle. At the bases of the giant pines—some of which may be more than 200 years old—are fire scars. Most of the mature trees survived the frequent fires that once raced through here. Their bark was thick and fire-resistant, and they had few lower branches to pass the flames up into the vulnerable upper branches. But that was before the white man interrupted the long reign of wildfire. Ironically, fire had actually helped to maintain the health of the forest. Grass fires, sweeping into the pines, burned off the accumulations of litter and killed many of the crowded younger trees. Tinder was thus removed before it could build to dangerous levels. _continues on page 40_ A Home for Wildlife Some animals indigenous to the Great Plains find a protected home in Devils Tower National Monument. Gone from this area are the bison that once roamed the prairie grasslands in great numbers, and the fastest plains animal, the pronghorn antelope, is rare. The most noticeable mammals here are the whitetail deer and the prairie dog (See pages 48-65 for pictures and text about the prairie dog and its predators), but with careful observation you can spot some of the smaller animals that inhabit the grasslands, woodlands, and rocky areas around the Tower. [Illustration: The raccoon, primarily a nocturnal creature, prefers woody or swampy areas and often dens in hollow trees.] [Illustration: The porcupine, which has up to 30,000 quills, dwells in the forest and often is seen in the tops of trees.] [Illustration: The longtail weasel usually lives in deserted burrows and preys on small mammals, some birds, and other animals.] [Illustration: The rare swift fox sometimes enlarges and inhabits an old prairie dog burrow. The red fox is more common here.] [Illustration: The pocket gopher is a remarkable burrower, creating up to 150 meters (500 feet) of tunnels close to the surface.] [Illustration: The thirteen-lined ground squirrel lives in a burrow in open areas, feeding mostly on seeds.]