The rating of biodiversity in arid and semiarid regions on the basis of ecological function and genetic traits of adaptation to severe environmental stresses produces significantly higher values, than that based solely on the commonly applied structural criteria of forms of life and levels of organization. The indirect driving forces of biodiversity impoverishment listed in the Global Biodiversity Strategy that are particularly effective in arid and semi-arid regions are (a) population growth, (b) economic systems and policies that fail to value the environment and its natural resources; (c) inequity in the ownership, management and flow of benefits from both the use and conservation of biological resources; and (d) weakness in legal and institutional systems. Keywords: biodiversity ratings, degraded habitat, impact, arid land, semi-arid land.