Figure 1-22. Protected from 

 grazing, mountain brome- 

 grass is maintaining itself in 

 competition with coneflower 

 {Rudbeckia occidentalis). 

 Note clumping of vigorous 

 aspens. (Cf. Fig. 1-22A.) 

 Aug., Manti-La Sal Natl. 

 Forest, Utah. (U. S. Forest 

 Service.) 



the plant, degree of hunger or desire of the animal for a partic- 

 ular kind of plant, and the availability of the plant are also in- 

 fluencing factors. 



Under close grazing a cow or sheep may graze poisonous plants 

 which remain untouched under moderate grazing. A very palat- 

 able species may be eliminated from a stand because of severe 

 grazing and may not be able to re-establish itself, thus less palat- 

 able plants are given opportunity to invade; for example, the re- 

 placement of grasses by annual weeds in prairie dog towns, 

 and by buffalograss in the northern Great Plains and mes- 

 quite in the semidesert grassland in the Southwest. Heavy graz- 

 ing has favored the spread of poisonous plants on wide areas of 

 western range lands (Figures 1-22 and 1-22 A). Overgrazing may 

 reduce competition to such an extent that species near the limits 

 of their geographic ranges can become dominant, as where 

 buffalograss replaces taller grasses in the northern Great Plains. 



Intensive grazing not only reduces the competitive capacity of 





Figure 1-22A. Under graz- 

 ing, Rudbeckia occidentalis 

 has almost replaced the 

 palatable mountain brome- 

 grass. Spruce trees invading 

 aspen grove in background. 

 (Cf. Fig. 1-22.) Aug., Manti- 

 La Sal Natl. Forest, Utah. 

 (U. S. Forest Service.) 



