RESEARCH SUMMARY 



The distribution of the pinyon-jutiiper woodlands of the Great Basin has been 

 mapped from LANDSAT-1 satellite photography. Dot grid analysis of this map 

 indicates that about 17. 6 million acres (7. 1 million ha) of this woodland are found 

 in the Great Basin. The distribution map was field checked and floristic data were 

 systematically taken at 482 stands on 66 of the approximately 200 mountain ranges 

 in the study area. 



A list of 240 positively identified species of vascular plants is provided to help 

 other workers initiate studies in the pinyon-juniper vegetation type. 



In this study, variations in total vegetal cover are related to latitude, longi- 

 tude, and elevation. Vegetal cover increases strongly with elevation and slightly 

 with latitude. Longitudinal patterns are related to increases in average elevation. 

 The greatest average vegetal cover is found in the higher, central portion of the 

 Great Basin. Sorting of the tree species is due more to elevation than latitude or 

 longitude. Junipers occupy the lower, drier elevations, whereas pinyons increase 

 at higher elevations. Double-needle pinyon is found more frequently in the south- 

 eastern Great Basin where more of the rainfall comes during the summer. 



