Grass-shrub rangelands occupy extensive acreages in southeastern Arizona and southwestern New Mexico between elevations of 3,000 and 5,000 feet. At lower elevations, the grass-shrub type merges with deserts dominated by creosotebush².  At higher elevations, the type forms a transition with chaparral, pinyon-juniper, or oak­woodland types (fig.1). Perennial grasses are the mainstay of the forage supply but browse species and annual grasses are sometimes important.

Sustained high production of perennial grass forage depends upon stocking the proper number of animals, grazing at appropriate times, and providing for optimum distribution of livestock. The usual practice is to graze the ranges yearlong. Annual or periodic adjustments in number of grazing animals are necessary because of wide variations in forage production. Seasonal adjustments are also helpful. Grazing can often be planned to make summer use of abundant annuals at lower elevations, spring use of ranges where browse is abundant, and winter use of ranges where black grama is an important component.