ABSTRACT
This chapter discusses how these environmental factors interact with plant strategies to produce the observed mosaic of the communities and proceeds to a broad discussion of the communities themselves. As will be discussed in more detail subsequently, the distribution of the precipitation does vary by season within the deserts, but in all cases low year-round availability of water severely limits vegetation productivity. In the topographically defined patches, the general pattern observed is that precipitation increases and temperature decreases as elevation increases. Whittaker, R. H. and W. A. Niering took a different approach on the Santa Catalina Mountains, a sky island dominated by the Mount Lemmon (9156 ft) in southern Arizona. The climate of this type is defined not by precipitation but by temperature and will not be considered in detail due to the limited extent of its occurrence in the southwestern region.
