14 A PROTECTED STOCK RANGE IN ARIZONA. 



urged — a system of grazing which it is well within the capacity of 

 the land to maintain. 



A number of native grasses have been caused to spread success- 

 fully by gathering the seed in advantageous localities and simply 

 scattering it where the ground was badly denuded. Better results 

 have been obtained when seeding was done the last of June or the 

 first of July. When sown in autumn the ants pick up too many of 

 the seeds. Beneficial results have been secured in this way by the 

 use of the seed of Andropogon saccharoides, Bouteloua vesiita, and 

 B. rothrockii. Less positive results have been secured by the use 

 of native seed of Bouteloua curtipendula and Leptochloa dubia. Indif- 

 ferent results have been secured with Bouteloua oligostacJiya. It 

 should be noted that the last is a very important grass on the east 

 side of the Santa Rita Mountains, but, so far as the writer knows, 

 it does not occur on the northwest side of the divide except in one 

 small, well-established patch. The origin of this is not certain, but 

 it is believed that it was established by seeding done in 1901. It is 

 a beautiful, vigorous growth in a place which was badly denuded 

 at that time. 



The above illustrations of the successful use of native species are 

 important and interesting, but they have no applicability to open- 

 range conditions. However, where the land is under fence and seed 

 can be secured in the vicinity without too much expense, improve- 

 ments can be made in very badly trampled areas. When the roots 

 of the native growth are not completely destroyed, it is questionable 

 whether in such situations as this recuperation would not occur fully 

 as rapidly by proper protection from overgrazing without the use of 

 seed as with it. 



It must be remembered that the chances of failure of seed in such 

 a region are very great. It is not necessary to discuss at length the 

 contributing causes. They are many. The most important are the 

 irregularity and the uncertainty of the rainfall. 



TEMPORARY CHANGES IN VEGETATION. 



The most striking changes in vegetation are those which take 

 place from year to year in annual plants, and this is always noticeable 

 in any region where the annual vegetation predominates. As a con- 

 crete example, the growth upon one of the inclosures in 1907 may 

 be compared with that of 1908. In a badly denuded portion of one 

 of the fields a blue-flowered, aster-like composite (MacTialranthera sp.) 

 was decidedly conspicuous. It was estimated that in 1907 one 

 could have cut with a mower at least 500 pounds of dry matter to the 

 acre from a large area. In 1908 one would have been obliged to cut 

 not less than 30 acres to secure 500 pounds. The only place that the 

 plant grew the second year was along washes and rivulets, which, 



177 



