22 A PROTECTED STOCK RANGE IN ARIZONA. 



They have made a very perceptible increase within the writer's 

 acquaintance with the area. The prediction is ventured that the 

 time is coming when these foothill grassy areas, which now have only 

 an occasional small shrub, will be as shrubby as the deserts and lower 

 foothills below them, if not more so. 



Some of these shrubs do, of course, furnish some feed, but here, as 

 elsewhere, their growth will be largely at the expense of grasses. 

 For a long time the lower foothills, arroyos, and general desert mesas 

 have been shrubby, and the gently sloping tables between the arroyos 

 and the upper foothills are slowly becoming so. 



It will doubtless be impossible to depict all the agencies that are 

 bringing about these changes. It is quite certain that the operations 

 here of the Bureau of Plant Industry have had no influence, for the 

 shrubbery has thickened up on the outside of the inclosure, where 

 the grazing has been very heavy, apparently as much as on the inside. 

 The probability is that neither protection nor heavy grazing has much 

 to do with the increase of shrubs here, but that it is primarily the direct 

 result of the prevention of fires. There never was a time when the 

 shrubby lower foothills and desert mesas produced vegetation enough, 

 except in limited localities, to allow fires to spread, but the grassy 

 foothills, which constitute the upper half of our inclosure, produce 

 sufficient vegetation to burn readily, at least every other year, at 

 the present time. Previously, before the country was stocked, it 

 probably produced more grass than it does now, and was frequently 

 burned over, the fire extending as far down as vegetation would per- 

 mit. Such burning did comparatively little injury to the grasses, 

 but was very destructive to all small shrubs; consequently, these were 

 able to exist only along the sandy washes, where the grasses were 

 least productive, and upon the lower areas, where fires did not molest 

 them. 



Upc'i the brushy deserts below, the rainfall is so scanty that the 

 grass produced is not sufficient to allow fires to spread. Upon the 

 mountains above, the moist season is more prolonged, the grass 

 remains green longer, and the surface is more broken, often with 

 sheer declivities, which are bare of vegetation, all of which render 

 burning less probable. It must be remembered that frequent burn- 

 ings are not necessary here to keep down brush. Possibly with com- 

 parative freedom from grazing a fire once in ten years would suffice 

 in such an area, because growth is very slow. 



The memory of early stockmen is not sufficiently retentive to give 

 us much reliable information regarding the location and density of 

 brush upon these areas when their operations began, so it is necessary 

 to make inferences from changes which are occurring now under the 

 changed conditions. Trained observers have not been sufficiently 



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