CHAPTER Vni 

 PINON AND JUNIPER 



General Conditions. Location and Extent. — This is the type 

 of woodland which occurs on the foothills of the Rocky Moun- 

 tains in western Texas, New Mexico, Arizona, Colorado, Utah, 

 Nevada, California, Idaho and Oregon. Above it lies the western 

 yellow pine and below it stretches the plains country with its 

 sparse vegetation of sage brush and buffalo grass. 



The climate of the type may be characterized as a hot, dry one, 

 but as might be expected in a typ)e with such a wide range there 

 is a considerable local variation. The mean annual temperature, 

 for example, ranges from 65 degrees to 45 degrees. With the 

 annual precipitation there is less variation. It is quite uniformly 

 10 to 15 inches. But again, the length of growing season differs 

 greatly from north to south. In New Mexico five to six months 

 are free from frost whereas barely four months have mean annual 

 temperatures above 32 degrees in the northern part of the types 

 range. 



The topography and soil are varied and do not seem to have 

 any controlling influence on the distribution of the type. Gen- 

 erally, however, it occupies a well drained slope with a deep 

 loamy soil but the type is foimd on shallow soiled hillsides pro- 

 vided the climatic conditions are right. 



The two species which give their names to the type are the only 

 arborescent forms which occur in any abundance. The pinon, 

 Pinus edulis, is not more abundant numerically but the larger 

 size which it attains and the edible character of its seeds makes 

 it the more important commercially. The junipers, Juniperus, 

 are often more numerous individually but their small size makes 

 them less valuable for firewood and hence they are the subor- 

 dinate species. A striking feature of the type is the openness of 

 the stands. The trees are scattered with open places in between 



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