20 



BULLETIN" 1405, IT. S. DEPARTMENT OF AGRICULTURE 



early range for fall grazing. The stage of development of the 

 forage in the aspen-fir belt is usually the determining factor as to 

 when the livestock should be moved from the oak-brush belt in the 

 spring. 



If the forage on the spring range is comparatively more abundant 

 than that on the summer range, and the whole range is stocked on 

 the basis of utilizing all of the forage, the animals should be held 

 on the early range so long as there is sufficient palatable feed avail- 

 able there to keep them in thrifty condition without overgrazing. 

 With limited summer range and abundant spring range, more ani- 

 mals will be maintained in good condition without injury to the 

 forage crop in any type if they are held on the lower lands as late 

 as possible. With a good balance in the grazing capacity of the 

 spring and the summer range, on the other hand, the stock may be 

 admitted to the summer range as soon as the forage there is ready 



Phenoloqicaf 



3C>*O 



SO f> 



o 



70 fh 





OAK BRUSh 



TYPE 



Ele motion 



7,200 ffr 



■/ 









Moy/O 













May 20 



















May so 











3 















SPRUCE F/fi 



TYPE 



E/eyot/on 



/ 0,050 Fee 



July / 

















July/c 















Avj.8 































3 



Legend 



S&Afi South Exposures 



\ I North Exposures 



Fig. 8. — Average phenological values for north and south exposures — 1920 forage 

 development in the oak-brush type occurs earlier on south exposures than those 

 facing the north. Increase in elevation results in less variation of plant develop- 

 ment between exposures 



for cropping. With limited spring range and abundant summer 

 grazing grounds, which is often the case on national forests and is 

 conspicuously so in those of the Wasatch Mountains, the situation 

 becomes more complicated. Under such conditions it is necessary 

 either to admit to the spring range at the beginning of the grazing 

 season only a portion of the stock capable of being carried on the 

 summer range, allowing the remainder to come on the range and 

 pass immediately to the summer range when the summer forage is 

 ready, or to delay the admission of all the animals until such a date 

 that the summer range will be ready for grazing when they have 

 properly utilized the forage on the spring areas. 



In some localities there are areas of spring range, limited in size, 

 where scarcity of water is the controlling factor in the period of 

 use. Early in the spring, owing to melting snow and occasional 

 showers, there is an ample water supply; but with the approach of 



