It is common knowledge that continued overgrazing, such as is prevalent on the semidesert ranges of the Southwest, reduces the stand of desirable forage plants and leads to serious range depletion, especially during periods of drought. Such depletion allows erosion of the valuable topsoil layer and permits rainfall to run off in torrential floods, with consequent damage to agricutlural lands and urban property in the valleys. Native vegetation, therefore, plays an improtant role not only in range conservation and improvement, but also in the protection of watersheds.