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Show The Transition Zone of the foothills and lower mountains probably attracts more vacationists than any other because it is the principal retreat of those seeking to escape from the summer heat of the lowlands. The location of this zone at the lower mountain levels usually renders it easily accessible at all seasons, while the coolness which accompanies its ample precipitation makes it the principal zone of winter sports. In the Colorado River Basin, water is most plentiful in the Transition Zone, so that it includes most of the best natural fishing areas, and for similar reasons the finest forests. With this abundance of vegetation are associated most of the big game animals, affording maximum opportunities for hunting and wildlife photography. In fact, nearly every form of outdoor recreation may be found in the Transition Zone and many kinds reach their highest development there. The Boreal Zone is the high mountain recreational region. In the northern half of the basin it is visited nearly as frequently as the Transition Zone because it extends to fairly low levels. However, in the southern half of the basin it is, as a rule, sufficiently difficult to reach that only those who can appreciate its wilderness character are likely to penetrate it very deeply or permanently. High mountain recreational developments usually are restricted to the general vicinity of the relatively few roads that penetrate Boreal regions, and such developments are further restricted in their operations by the extreme shortness of the summer season. Camping, hiking, fishing, horseback riding, winter sports, photography, and the enjoyment of wildlife and rare flowers reach their culmination for many persons in this remote, and, to many, most beautiful and inspiring of all recreation regions. LIFE ZONES Because the basin embraces latitudes from Mexico almost to Yellowstone National Park, and altitudes ranging from 248 feet below sea level to 14,431 feet above sea level, all of the life zones of the United States are present except the Tropical Life Zone of southern Florida. These life zones are as follows: Boreal Zone.- In detailed studies of small areas this often is subdivided into three zones- Alpine, Hudsonian, Canadian- but these finer distinctions are needless here. This zone is characterized by the cool, moist climate of Canada and the northern coniferous forest belt of the United States. Winter snows are heavy and long- lasting. Total annual precipitation is from 23 to 60 inches or more. On the other hand, at the lower levels of the Boreal Zone in the arid Upper Green River Valley of Wyoming, annual precipitation may be as low as 15 inches in some localities. 1 The annual mean temperatures are in the neighborhood of 45° to 27° F. or less. Narrow tongues of the Boreal Zone extend far south of the main area along various high mountain crests such as the Rockies. With the increase in average temperature toward the Mexican border, the tongues give way to a series of scattered islands as the zone becomes restricted to the tops of the loftiest peaks. In the Colorado River Basin, the most reliable and conspicuous plant indicators of the Boreal Zone are the lodgepole pine, limber pine, whitebark pine, white pine, foxtail pine, white fir, alpine fir, Engelmann spruce, blue spruce, dwarf juniper, aspen, red elderberry, dogwood, and the blueberries. Extensive timber line grasslands and scattered high mountain meadows also occur in this zone. Some of the more interesting or conspicuous animals and birds that characterize the Boreal Zone are the pine squirrel, marmot, cony, snowshoe rabbit, lynx, red fox, marten, wolverine, goshawk, three- toed woodpecker, Rocky Mountain jay or camp robber, dark crow, and crossbill. Transition Zone.- The zone was given this name because it was considered to be essentially an area where the ranges of many northern ( Boreal) and southern ( Sonoran) plants and animals overlapped. Although this is to some extent true, the Transition Zone possesses a quite distinctive climate and a number of prominent and characteristic species of its own. In Wyoming, Colorado, and northern Utah, where the Boreal Zone covers all the major mountain masses, the Transition Zone occupies the foothills and higher valleys. Farther south, however, where the Boreal Zone is restricted to projecting tongues and isolated high peaks, the Transition Zone occupies most of the mountain masses, and is 1 Dr. John W. Scott, letter, 1946. 6 |
