RIBBONS OF GREEN THROUGH DESERT LANDSCAPES
FIGURE 6.21 Riparian forests and wetlands are generally areas of exceptionally high primary production and species richness in arid and semiarid landscapes, such as here along the San Pedro River in southern Arizona. Periodic flooding is essential for maintaining healthy riparian areas in arid lands, since many key riparian plant species require flooding for reproduction. By contrast, in many urbanized landscapes in arid and semiarid regions, such as the Salt River in Phoenix, riparian wetlands and forests have been nearly eliminated as watercourses have been dried and natural habitat replaced by engineered structures.
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