45 I- 



1600 1800 2000 2200 



2400 2600 



2800 



ELEVATION (M) 



FigvLTB 4. — Relationship of average total vegetal cover to elevation in woodlands sam- 

 pled on the 18 moimtain ranges with "detailed" dxxta. Vertical bars represent one 

 standard error. There is not a standard error bar at 2, 800 meters because only one 

 plot was available. 



variation in Tree Distribution and Dominance 



The trees are usually the first organisms thought of in describing the pinyon- 

 juniper vegetation type. It therefore seems worthwhile to consider the variation in 

 tree distribution and dominance. 



Figure 5 shows that Utah juniper occurs alone only along the northern boundary of 

 the study area and in a few places in the Bonneville Basin of western Utah. Pinyon 

 occurs alone only in the Excelsior Range along the California-Nevada border. Mixtures 

 of pinyon and juniper occur throughout the rest of the study area. 



16 



