THE PLANT COVERING OF THE EAETH 319 



country the usual result is that the slopes are soon stripped 

 of soil and neither forests nor anything else will grow. It is 

 not probable that rainfall is increased by the presence of 

 trees, but the water that does fall is better conserved in the 

 forest than in the open country, and the streams which flow 

 from the forested mountains are much more constant and 



FIG. 154. Wasteful lumbering 



The more valuable trees were cut, and the brush was allowed to lie upon the 



ground. Fire has destroyed not only the refuse but also the remaining trees and 



the young growth. There will be no second cutting for many years. Photograph 



by the United States Forest Service 



uniform than those that flow from a region whose slopes are 

 bare and rocky. For this reason forests are particularly 

 important when they are located upon the sources of streams 

 which supply water for irrigation in the lower valleys. 



The grasslands in their natural condition are useful mainly 

 for grazing (fig. 155). In the past a large part of the meat 

 supply of this country came from the cattle raised on the 

 great ranches which formerly occupied the Western prairies 

 and plains. A large part of these grasslands is so level and 



