Big sagebrush (Artemisia tridentata Nutt.) is the most common and widespread sagebrush species in the Intermountain region. Climatic patterns, elevation gradients, soil characteristics and fire are among the factors regulating the distribution of its three major subspecies. Each of these subspecies is considered a topographic climax dominant. Reproductive strategies of big sagebrush subspecies have evolved that favor the development of both regional and localized populations.