Journal ArticleLeaf carbon isotope ratios were measured on plants from the coastal portions of the Atacama Desert at Pan de Azucar and Paposo, Chile. Most species possessed C3 photosynthesis, although there were several CAM species, indications of some facultative CAM species, and only one C4 species. The carbon isotope ratios of the C3 plants are unusually high, even for species from arid ecosystems. These observations indicated that C3 species of the Atacama Desert were characterized by very low intercellular C0 2 concentration that averaged between 159 and 190 ppm, depending on the severity of the drought
