APPLIED ECOLOGY 



353 



rather well known because of several intensive studies in different 

 areas. Irrigation is necessary everywhere except on the best soils 

 in the sagebrush areas of the northern portion of the Great Basin. 

 Elsewhere, in addition to the need for irrigation, native species in- 

 dicate other necessities or precautions. 228 The tabulation on page 

 354 although specifically applicable only to the Sonoran Desert 

 region of Arizona and southeastern California, illustrates the prin- 

 ciples involved. 



FlG. 188. These productive fields and orchards in Hurrican Valley, Utah, 

 irrigated from the big ditch at left, are bordered on all sides by sagebrush 

 desert. Knowledge of natural vegetation and soil gained from such projects 

 makes possible confident statements of probable success or failure when 

 others are to be established— U. S. Forest Service. 



These generalizations indicate how natural vegetation may be 

 useful in determining regional land use. It is the details of local 

 conditions as indicated by native species that need more study. 

 If the equivalent cultivated and native species were known for 

 different soils, sites, and exposures, it would be possible to state 

 with confidence which fields should be cultivated and which 

 should be put to pasture or wood lot, as well as which crops 

 should be grown in a particular field. The more complete such 

 knowledge is, the more effectively land can be used, and the more 

 certainly land values can be fixed for sale and taxation. 



