GRAZING and forage production on national forests 51 



Experiment Station and in other parts of the Wasatch Mountains 

 of Utah indicate how this may be done. 



In the Wasatch Mountains the forage cover is of three major 

 types, which correspond with rather definite elevational zones — the 

 oak-brush (6,500 to 8,000 feet elevation), the aspen-fir (7,500 to 

 9,500 feet), and the spruce-fir (above 9,000 feet). 



In this region temperature and precipitation are the chief climatic 

 factors influencing the grazing period. During the main growing 

 season from June to September, inclusive, the mean temperature 

 decrease gradient for each 1,000 feet elevation from the oak-brush 

 to the spruce-fir zone is 4.05° F. Growth is delayed approximately 

 14 days on comparable areas with an increase in elevation of 1,000 

 feet. Low precipitation in the oak-brush zone is a limiting factor 

 in plant growth. Precipitation is appreciably greater in the more 

 elevated zones. Heavy snow in these zones delays the start of 

 growth. 



The proper time for grazing to begin on a range, or the time of 

 "range readiness," may be defined as the date in any one year when 

 the range first reaches the condition in which there is sufficient feed 

 to keep livestock in thrifty condition and when the stock may be 

 admitted without serious impairment of the growth and reproductive 

 processes of the more important forage plants. 



Early yield of forage is comparatively small if the herbage is 

 cropped when its average height is 4 inches or less. Grazing when 

 the plants are at this stage stunts the vegetation, and does not 

 satisfy the hunger of the animals because of the low feed value of 

 the short succulent herbage. 



It is advisable to use as a guide for range readiness the develop- 

 ment of the plant cover as a whole rather than of a few species. 

 The larger the list of plants used as indicators the more reliable 

 the result. 



The earliest plants on the range mature early and are exception- 

 ally high in water content and usually of low palatability. When 

 they are in full bloom the main forage species are seldom sufficiently 

 developed for grazing and the soil is soft and often boggy. They 

 therefore indicate range unreadiness. 



The proper development of the later-maturing herbaceous and 

 browse species, and especially the important forage plants, may 

 safely be used as a guide for determining range readiness. The 

 proper stage of development may be identified by height, size, or 

 flower stalk, or head production, depending on the species. The 

 grasses, for instance, should in general be about 6 inches in height 

 and the earlier-maturing ones should have flower stalks showing. 



The close of the spring grazing period is determined by (1) the 

 development and quantity of forage on the summer range, (2) the 

 grazing capacity of the spring range as compared with the summer 

 range, (3) the palatability of the forage on the early range and 

 the thriftiness of the animals grazed, (4) the water supply, and 

 (5) the need for and value of the forage on the spring range for 

 fall grazing. The close of the summer and fall grazing period is 

 governed largely by (1) proper utilization, (2) weather conditions 

 and the trampling of wet soil, (3) condition of the livestock, (4) 

 availability of forage elsewhere, and (5) water supply. On winter 



