Woody wetlands constitute a relatively small but extremely important part of the landscape in the southwestern United States. These riparian habitats support more than one-third of the region’s vascular plant species, are home to a variety of wildlife, and provide essential havens for dozens of migratory animals. Because of their limited size and disproportionately high biological value, the goal of protecting wetland environments frequently takes priority over nearly all other habitat types. In The Ribbon of Green, hydrologists Robert H. Webb, and Stanley A. Leake and botanist Raymond M. Turner examine the factors that affect the stability of woody riparian vegetation, one of the largest components of riparian areas. Such factors include the diversion of surface water, flood control, and the excessive use of groundwater. Combining repeat photography with historical context and information on species composition, they document more than 140 years of change. Contrary to the common...