INCREASED CATTLE PRODUCTION. 3 
and demonstrations in range management under conditions existing 
in southern New Mexico and similar country in adjoining States. 
The boundaries were slightly modified by Executive order of April 24, 
1916, and at present include about 200,000 acres. 
The eastern portion of the area, comprising about one-fourth of 
the total, is rough and broken and includes the west slope of the 
San Andreas Mountains, which reach a maximum elevation of about 
7,600 feet, both slopes of a narrow belt of rough, gravelly hills just 
west of the main mountains, and a series of narrow, poorly defined 
valleys between the two. The remainder of the Reserve is a com- 
paratively flat, or slightly rolling, plain, lying between elevations of 
about 4,100 and 4,700 feet, and broken only by a small mass of 
igneous mountains, the Dona Anas, at the southwest corner. 
The locality is one of the most arid in the Southwest. Records 
for 55 years at Mesilla Park, about 15 miles southwest of the Reserve, 
show an average annual precipitation of 8.63 inches, with precipita- 
tion for individual years as much as 17 inches and as little as 3.50 
inches. Temperatures as high as 106° are common in summer, and 
the region is subject to almost continuous high winds and, conse- 
quently, high evaporation. The soils of the plain are rather coarse 
to medium textured wind-blown sands, with patches of heavy adobe 
clay, usually with a rather high percentage of alkali, where water 
often stands until evaporated. The soils of the mountains and the 
outwash plains flanking them are coarse sands and gravels. 
Naturally, with this combination of poor soils, low precipitation, 
high temperatures, and high winds, the vegetation is comparatively 
thin and made up of drought-resistant, semidesert species. By far 
the greater part of the forage, perhaps 80 per cent, is furnished by 
perennial grasses, of which the most important are the grama grasses, 
three-awn, tobosa, drop-seed, muhlenbergias, burr6 grass, and wolftail.! 
On large areas of the foothills and mesa, black brush, creosote bush, 
and mesquite predominate; but black brush and creosote bush are 
worthless as forage, and the mesquite is of low value. In figure 
2 the vegetation is inetd into range types for all of the Reserve 
except the mountain portion. . 
1 Black grama (Bouteloua eriopoda) is the most important grass on the Ieserve. Dlue grama grass (B. 
gracilis) and hairy grama grass (B. hirsuta) are found only in the mountains and foothills. B. curtipendula 
is found in the mountains and on the mesa. 
Next to the grama grasses in importance are three-awn grasses (known locally as ‘‘needle grasses’’ )— 
Aristida longiseta, A. pansa,and A. purpurea. 
Tobosa grass ( Hilaria mutica). 
The drop-seed grasses include several species, the most important being Sporobolus cryptandrus, S. flex- 
uosus, S. wrightii, S. airoides, S. auriculatus. 
The most important species of muhlenbergias are Muhlenbergia gracillima, and M. porteri. 
Burro grass (Scleropogon brevifolius). 
Wolftail (Lycurus phlecides). 
Blackbrush ( Flourensia cernua). 
Creosote bush ( Covillea glutinosa). 
Mesquite (Prosopis glandulosa). 
