Technical Abstract: Desertification is an active process in the Chihuahuan Desert that is typified by a vegetation transition from desert grasslands to desert scrub. Throughout much of geological time, deserts have waxed and waned without human intervention. Currently, it is difficult to segregate human and nonhuman causes. One obvious cause of this transition is a dynamic interaction between plant species with and without specific adaptations to large animal herbivory. An examination of vegetation change with time reveals that deserts are complex, chaotic, and often catastrophic. New models are being developed to deal with the resulting uncertainty. These models include complex adaptive systems and adaptive management. These models are discussed and applied to conditions prevalent in the Chihuahuan Desert.