GRAZING EANGES IN SOUTHEElSr ARIZONA. 33 



If allowance is made for the facts (1) that these pastured areas 

 produce more feed than other parts of the area under observation, 

 (2) that they are carrying more under the present form of manage- 

 ment than they would if an average number of animals were kept 

 on them continuously, and (3) that there is some indication that they 

 are slightly overstocked, it is seen that the results obtained from the 

 pasturing experiments are in reasonably close agreement with the 

 average for the whole reserve derived by other means and presented 

 elsewhere in this bulletin. (See p. 21 et seq.) 



MISCELLANEOUS NOTES. 



The effects of fire. — The complete protection of the reserve for a 

 number of years has resulted in a rather heavy crop of dry grass, 

 which burns readily, especially in the dry, hot weather of May or 

 June, just before the summer rains begin. Several such fires have 

 occurred, due to lightning, carelessness of passers,' or incendiarism. 

 The onlj^ serious damage they do is to burn off the fence posts and 

 let the fences fall. These fires are always extinguished as quickly 

 as possible after they start, but sometimes considerable areas have 

 been burned over. Attention has been called to the effect on the 

 mesquite bushes. The spines of the cacti are usually singed off, and 

 some of the stems blistered, and a few are killed. Opuntia spinosior 

 seems to suffer more seriously than any of the other species. In 

 June, 1914, occurred one of the largest and hottest fires, which 

 burned over about four sections of the heaviest grass. Along the 

 arroyos where the grass was highest and thickest the mesquite 

 bushes were killed completely in several places, and many were 

 killed back to stumps. The following growing season on the burned 

 area there was a much larger proportion of annuals in the surmner 

 collections and a particularly noticeable abundance of one grass, 

 Bouteloua parryi, which has not been observed in any abundance 

 recently. It was common in many parts of the reserve in the earlier 

 years of the experiment. Whether or not the burn was responsible 

 for these occurrences the writer is unable to say. The fire was doubt- 

 less responsible for a noticeable decrease in the hay crop obtained on 

 part of the burned area this season.^ Of the grasses, Bouteloua 

 erippoda and Heteropogon contortus suffered most, though old stools 

 of Aristida divaricata also showed retardation and some killing. 



The mesquite hean crop. — An important part of the forage of this 

 region is furnished by the herbage and flowers of the cat's-claw 

 {Acacia greggii) and the mesquite {Prosopis velutina)^ as well as by 

 beans of the latter. Two measurements were made of the crop of 

 mesquite beans from medium-sized trees in 1914. The blossoming 



1 See Table IV, p. 24 : Proctor's records for 1914. 



