The reciprocal effects of vegetation and soils have long been a subject of speculation and conjecture. In the management of any natural land area the problem of interpreting vegetational expression is especially important. The effects of native vegetation on soils and the effects of the soil on the vegetation have been studied and observed for many years. The arid-desert range lands have been studied and observed for many years. The arid-desert range lands have been studied least and as a result are not well understood. As human populations increase there will be additional need for agricultural production, and these lands may be put to higher use, perhaps even to irrigated crop production. Basic to increasing the productivity of these lands is an understanding of the vegetation they are now supporting, what they supported prior to their use by domestic livestock, and why the present vegetation grows to the exclusion of other vegetation types.