GRAZING TYPES. 273 



Formations as indicators. As has just been seen, the grazing value of a 

 climax formation is determined primarily by the vegetation-form, though 

 other factors enter locally to modify it more or less. The grassland cUmax 

 is by far the most important of all, and there is Uttle doubt that its develop- 

 ment and extension have controlled the evolution of grazing animals in the 

 past. The fact that the word graze is formed directly from grass proves that 

 grassland has long been the primary grazing type, and that all others are 

 secondary, resulting from the natural extension of grazing into scrub and 

 forest. The alpine meadow ranks next to prairie and plain in primary 

 grazing value, though the short season finds expression in the low growth- 

 form as well as in the short period for grazing. The savannah marks the 

 transition from primary grazing land, i. e., grassland, to scrub. In spite of 

 the unique importance of the latter for mixed grazing, its actual grazing value 

 is secondary, as is indicated by the appUcation of the word browse to it. Of 

 the scrub climaxes, the chaparral usually stands first in importance, the sage- 

 brush next, and the desert scrub last, though this varies greatly with the 

 grouping of the various dominants. Of the forest formations, montane 

 forest has the greater value, due largely to the open grassy nature of the 

 yellow pine consociation. The woodland resembles the latter more or less 

 and often ranks next to it in amount of grazing. The subalpine forest varies 

 greatly in importance. The grazing value of its meadows, natural parks, and 

 aspen areas is high, but the cHmax forest is usually too dense and closed to 

 permit the growth of a uniform ground cover. This is even truer of the 

 luxuriant Coast forest, in spite of the fact that the latter often exhibits a 

 dense tangle of shrubbery. 



Associations as indicators. The indicator significance of an association is 

 essentially that of the formation to which it belongs. As a subdivision, it 

 represents a closer response to regional conditions, and the various associations 

 of a climax permit the recognition of more or less different grazing values. 

 This is characteristically true of the grassland and alpine meadow formations. 

 It holds to a somewhat smaller degree for the scrub and is least evident for the 

 forest cUmaxes, in which the number and extent of serai conmiunities are 

 more significant for grazing than the cUmax areas themselves. 



In determining the relative grazing value of the associations of the grass- 

 land chmax, this is found to depend upon density, height, and mixture. Upon 

 this basis, the subclimax prairies are perhaps the most valuable, though the 

 true prairies are nearly as valuable, and in some cases even more so. The 

 mixed prairies come next, and are followed by the short-grass plains. The 

 bunch-grass prairies at their best may equal the latter, but generally the stand 

 is too open. While the desert plains are of the same character as the short- 

 grass association, the bunch habit is more pronounced and the total production 

 usually less. Quite apart from the question of yield, however, is that of time 

 of development and ability to cure on the ground. From this standpoint, 

 the mixed prairie of tall Stipa or Agropyrum, and short BuWilis, Bouteloua, or 

 Carex, or the transition area of Andropogon and short-grasses has a distinct 

 advantage. The tall-grasses either develop earUer or grow with such rapid- 

 ity as to furnish the bulk of spring and sununer feed, while the short-grasses 

 become cured in late summer to furnish feed for fall and winter. Finally, 

 it must be recognized that the tall-grass associations are agricultural indicators 



