NATURAL AREAS AND REGIONS 



233 



tail rabbit (Sylvilagus audubonii group), 

 and black-tailed jackrabbit (Lejnis cali- 

 fornicus group) and woodrat {Neoioma 

 sp.) inhabit this zone, but are not 

 confined to it. 



YELLOW PINE TYPE (TRANSITION ZONE) 



Western yellow pine (Pinus ponderosa 

 sco-pulorum) forms stately forests on the 

 tablelands and lower mountain slopes 

 between altitudes of 7000 and 8500 ft. 

 The parklike character of the stands, 

 the ease with which travel is accom- 

 plished, the delightful summer climate 

 and the wealth of plant and animal life, 

 give these forests a peculiar charm. 

 The mean annual precipitation totals 

 between 20 and 25 in. and the mean 

 annual temperature is around 45°. 

 Grasses dominate the herbaceous vege- 

 tation, but brilliant flowered plants lend 

 color to the landscape during the sum- 

 mer rainy period of July and August. 

 Birds are represented by the pigmy 

 nuthatch, long-crested jay, western 

 robin, chestnut -backed bluebird, Mearns 

 quail and wild turkey. Among the 

 characteristic mammals are Abert squir- 

 rel (Sciurus aberti group), white-tailed 

 deer, mule deer, coyote, wolf (Canis 

 mexicanus), and black bear (Ursus 

 americanus group). Since this forest 

 is the main source of saw timber in the 

 Southwest, natural conditions will be 

 disturbed by lumbering, though not to 

 the extent of destroying forest con- 

 ditions. Extensive areas exist which, 

 because of the lack of transportation 

 facilities, will probably remain unex- 

 ploited for fifty years. Grazing inter- 

 feres with the normal development of 

 herbaceous vegetation, but this in turn 

 aids in the control of fires which other- 

 wise would endanger the forest itself. 



DOUGLAS FIR TYPE (CANADIAN ZONE) 



Douglas fir {Pseudotsuga taxiJoUa), 

 associated with white fir {Abies con- 

 color), limber pine {Pinus fiexilis), and 

 several minor species, forms dense stands 

 on cool slopes between altitudes of 

 8000 and 10,000 ft. Undergrowth is 



usually light and consists mainly of 

 shrubs and broad-leaved herbs. Natu- 

 ral reproduction of forest trees is usually 

 abundant. Extensive areas in this 

 forest type have been burned over and 

 have grown up to aspen. In many cases 

 the aspen thickets are being invaded by 

 conifers which will eventually replace 

 the aspen. The mean annual tempera- 

 ture is about four degrees lower, and the 

 precipitation about five inches higher 

 than in the yellow pine type. Cutting 

 is progressing rapidly in certain locali- 

 ties; in others rugged topography or 

 distance from lines of transportation 

 will bar the lumberman for many years 

 to come. Grazing is less intensive than 

 in the Yellow Pine type. Characteris- 

 tic birds and mammals are the Clarke 

 nutcracker, blue grouse, wild turkey, 

 porcupine {Erethizon epixanthum), red 

 fox {Vulpes fulva group), and spruce 

 squirrel {Sciurus fremonli group). 



ENGELMANN SPRUCE TYPE (UPPER 



CANADIAN ANT) LOWER HUD- 



SONIAN ZONES) 



The densest forests of this region are 

 composed of Engelmann spruce {Picea 

 engelmanni), associated in varying de- 

 grees with alpine fir {Abies lasiocarpa), 

 corkbark fir {Abies arizonica), and 

 bristle-cone pine {Pinus aristata). As 

 in the Douglas fir type, extensive areas 

 have been burned and have grown up to 

 aspen which will eventually give way to 

 the conifers. Since the highest slopes 

 are above the range of aspen, burns in 

 such situations remain bare until re- 

 stocked by coniferous trees. Exploita- 

 tion has been limited usually to the re- 

 moval of ties and poles. Much of this 

 forest will remain undisturbed by cut- 

 ting for an indefinite period because of 

 the difficulties encountered in transport- 

 ing the timber to market. The Engel- 

 mann spruce type extends to the upper 

 limit of tree growth which is encountered 

 at around 11,500 ft. Precipitation is 

 little, if any, higher than in the Douglas 

 fir tvpe, but the temperature is lower. 

 Snow lies on north exposures until 

 July. Undergrowth is usually sparse. 



