BRYCE CANYON A Geologic and Geographic Sketch of Bryce Canyon National Park

A GEOLOGIC AND GEOGRAPHIC SKETCH OF BRYCE CANYON NATIONAL PARK

CLIMATE, VEGETATION, ANIMALS

Bryce Canyon National Park may be said to have two climates, determined chiefly by differences in altitude. An ascent of 2,000 feet in a distance of 5 miles brings changes that on flat lands would require a traverse from Arizona to Montana. Generally in the valleys at altitudes below 6,500 feet the summers are long and hot and the winters fairly short and cold, and the yearly, monthly, even daily rainfall ranges widely. At Tropic, where the mean annual temperature is 62.9, temperatures of 100 to 101 degrees are recorded for June, July, August and September, and -9 to -32 degrees for November, December, January, and February. At this station the mean annual rainfall (12.62 inches) is made up of monthly means of 0.00 to 1.85 inches.

On the plateau top, at altitudes of 8,000 to 9,000 feet, an uncomfortably cold season that extends from November to March is followed by months of delightfully cool weather. At Bryce Canyon National Park headquarters the mean monthly temperatures range from 8.2° (January) to 64.5° (July); and the daily temperatures, from 86° to -20°. The annual rainfall at this station is 18.41 inches and, except for the relatively dry months, April and October, is fairly evenly distributed. Snowfalls exceeding 20 inches, recorded for the months of November to May, make up a considerable part of the annual precipitation.

In response to climatic conditions, the plants of Bryce Canyon National Park are roughly arranged in three zones within which certain species are dominant: Upper Sonoran Zone, pinon-sage brush belt, altitude 3,000 to 7,000 feet; Transition Zone, yellow pine belt, 7,000 to 8,500 feet; Canadian Zone, spruce-aspen belt, above 8,500 feet. The Upper Sonoran Zone is the natural habitat of the pinon pine and the Utah juniper (cedar)—trees that grow in poor soil and good soil, in canyons, on ridges, and on cliff sides in such abundance as to justify the term "pigmy forest." Among these trees where the soil is deep, particularly in valleys, sage brush grows profusely. At canyon heads scrub oak forms dense thickets, and in favorable places such shrubs as cliff rose, service berry, manzanita, mountain mahogany, squaw bush, clematis, and herbs that include larkspur, nightshade, dogbane, stick weed, and snake weed are conspicuous. Some cool canyons and open valleys are lined with cottonwood, willow, water birch, and maple.

The Transition Zone is dominated by yellow pine—more than half of the trees in the park. For some six miles the park highway is lined with big, tall, widely spaced pine trees—the eastern edge of the attractive forest that covers large parts of the Paunsaugunt Plateau. Underneath them and in open spaces between, roses, iris, goldenrod, primrose, snow berry, rabbit bush, mustard, Indian paint brush, mariposa lily, sweet clover, flax, tall bright-stemmed grasses, and many species of asters and astragulus make a flower garden of exceptional beauty. With increasing altitude, plants of the Transition Zone gradually give way to those of the Canadian Zone. Along the rim road of the Bridge Hollow the yellow pine and flowering herbs become fewer, the firs and aspen become more abundant until, at Rainbow Point, the forest consists chiefly of limber pine, foxtail pine, white fir, Douglas fir, and aspen which forms compact groves or stand alone. Between the trees grow violets, cranesbill, gentians, blue bonnet, yarrow, cinquefoil, bell flowers, strawberries, six species of erigeron and, in suitable places, many of the grasses and flowering plants found also in the Transition Zone. Though in mass the vegetation of the three zones is distinctive, the range in kind of soil, exposure to the sun, and amount of ground water are so great that the zonal boundaries are zigzag lines with upward and downward departures of hundreds of feet. Thus of some 300 species of plants recorded for the park, 71 species are listed in the Lower Sonoran and Transition Zones, 34 species in the Transition and Canadian Zones, and 29 species in all three zones.

The fauna of Bryce Canyon National Park is that common to pine and pinon forests of Utah. Of the 30 mammals listed, 9 are carnivorous and 20 rodents. Most in evidence are skunks, gray fox, bobcat, rockchuck, Fremonts squirrel, chipmunk, pocket gopher, white-footed mouse, porcupine, and mule deer. The rich and varied bird fauna of the park includes hawks, doves, owls, and 59 species of passerine birds. Among the song birds are wrens, thrushes, vireos, warblers, and tanagers. For most reptiles the region is too cold. The once common beavers (Paunsaugunt—home of the beaver) have disappeared and bears are nowadays rarely seen.