16 A PROTECTED STOCK RANGE IN ARIZONA. 



species, have, it is true, disappeared, but they were not driven out by 

 annuals, but, on the contrary, by the rancher's cattle. 



The annual grasses of this region, such as Bouteloua aristidoides 

 and Aristida bromoides, are not much relished by stock. They have 

 harsh, hard glumes which penetrate the flesh. They dry up early, 

 leaving but little substance, and, more than all this, they pull up by 

 the roots when grazed and carry with them sand and dirt. They are 

 therefore not eaten while the perennials are available. When the 

 latter become impoverished by excessive grazing the former flourish. 

 The ranges have therefore at present a larger proportion of weedy 

 annuals, not because the latter are more aggressive, but because the 

 former have been impoverished and to a large extent in many sec- 

 tions killed out by overgrazing. 



One thing at least has been conclusively proved in this experiment, 

 i. e., that the perennials which once flourished here and which have 

 been decidedly injured by stock will again regain their ascendency 

 over the weedy annuals when given a measure of protection. The 

 Bouteloua roihrockii and Bouteloua bromoides areas were not only less 

 productive of these perennial grasses when the inclosure was made 

 but were actually more productive of the annuals Bouteloua aristi- 

 doides and Aristida bromoides. (See Pis. II and III.) The gradual 

 encroachment of the perennials upon the region of annual grasses 

 has been one of the most notable features since the area was inclosed, 

 and is yet in all probability only partially accomplished. 



The regaining of ascendency by the perennials is slow here, much 

 slower than in regions favored by a more equitable rainfall. As 

 stated elsewhere, it is only in an occasional season that seed of the 

 perennials appears to find conditions congenial for growth. This, 

 coupled with the fact that the annuals invariably encroach at this 

 altitude whenever the perennials are injured, renders the process of 

 recuperation slow here compared with that in northern regions of 

 more favorable rainfall and a less easily eroded soil. 



On the other hand, the increased growth of an even partially pro- 

 tected area is phenomenal. One of the inclosures completed very late 

 in 1907 can be distinguished at the present time for miles by the differ- 

 ence between the character of its vegetation and that of the vegeta- 

 tion outside, and it has been grazed continuously at that, but only 

 moderately. 



Last season one of the fields inclosed was as badly grazed as the 

 Macaranthera area already referred to, but grew a fine crop of a 

 yellow annual composite. Although it was in one of the best peren- 

 nial-grass regions on the west side of these mountains, there was 

 practically no grass there except a poor growth of the six-weeks' 

 varieties. This season there is, of course, after such excessive graz- 



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