GEAZING AND FORAGE PRODUCTION ON NATIONAL FORESTS 



41 



than 100; where the herbage was removed twice the index figure 

 is more than 250, and where the herbage was cropped once it is 

 more than 300. In violet wheat grass an even more remarkable 

 contrast obtains. These figures represent somewhat closely the 

 relative quantity of forage which the plants may produce in the 

 following season. 



APPLICATION OF RESULTS IN RANGE MANAGEMENT 



These results clearly indicate the necessity of so adjusting the 

 number and distribution of livestock that the important forage 

 plants will not be kept so closely grazed throughout the season as to 

 be unable to make the necessary growth to maintain their vigor. 

 On the other hand, they show that two or, in some types, three mod- 

 erately close croppings in a season, provided the first is late enough 

 and the interval between each two is sufficient for the vegetation 

 quite to recover from each, ordinarily do not seriously affect the 

 yield and vigor of the forage plants. Frequent close cropping of the 

 herbage following seed maturity may cause excessive declines in 

 yield and later maturity in succeeding years. These results indicate 



PLANT, 

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MOUNTAIN BROME. 

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PLANT 

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Fig. 16. — Relative index of chemical constituents of roots of an average plant repre- 

 sentative of vegetation whose herbage was cut three successive years with varying 

 frequency. (Average plants collected at end of growing season, 1919) 



that the forage on range set aside for spring and fall use may be 

 grazed closely at the time of vegetative readiness in the spring, and 

 again in the fall without injury. If the important forage plants on 

 a range become closety grazed before the end of the growing season, 

 however, the livestock must be removed from that range until the 

 forage plants recover their vigor in order to prevent injury. If the 

 livestock remain on the range after it has become closely grazed, the 

 growth is insufficient to prevent too frequent cropping or to furnish 

 herbage of good food value. 



Sheep may graze over a range two or, on types that support hardy 

 plants, even three times during a three-months' late summer season 

 without injuring the forage plants, provided the grazing at each 

 time is not too close. If the range is so stocked that it must be 

 grazed four or more times, however, injury to the forage plants is 

 sure to occur. It is not possible to handle cattle on open ranges so as 

 to graze the same range closely and then allow a rest several times 

 during a summer season, as may be done with sheep under herd. On 

 cattle ranges grazed season long, the number should be adjusted to 

 give close, though not excessive, utilization by the end of the grazing 

 season. 



