12 VEGETATION OF A DESERT MOUNTAIN RANGE. 



communities which may be seen in southern Texas and in California, as 

 well as in similar situations in Arizona and New Mexico; the last is 

 essentially like the great body of yellow pine forest which stretches 

 from southern Jalisco to British Columbia, or like the fir and Douglas 

 spruce forests of the Rocky Mountains. These three major regions 



9,000 

 8.000 

 7,000 

 6,000 

 5,000 

 4,000 

 3,000 



9.000 

 8,000 

 7,000 

 6.000 

 5,000 

 4.000 



3,000 - 



Fouquieria splendens 



Quercus emoryi 



Dasyiirion wheeieri 



Quercus nypoieuca 



FIG. 1. Diagram showing vertical distribution of Desert, Encinal, Pine 

 Forest, and Fir Forest in relation to slope exposure, together with dia- 

 grams showing effect of slope exposure on vertical distribution of Fou- 

 quieria splendens, Dasyiirion wheeieri, Quercus emoryi, and Quercus 

 hypoleuca. 



constitute the most natural and easily distinguished subdivisions of 

 the vegetation, and depend for their distinctness on the radical dis- 

 similarity of the dominant types of plants in each. They may best be 

 designated by the simple terms Desert, Encinal,* and Forest. The 



* The Spanish word "encinal" signifies a grove or forest of evergreen oaks, being derived from 

 encina, evergreen oak. The suitability of the word was, suggested by Prof. J. W. Harshberger. 



