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The climatology of two succulent plant families: Cactaceae and Crassulaceae

1978; Canadian Science Publishing; Volume: 56; Issue: 15 Linguagem: Inglês

10.1139/b78-208

1480-3305

James A. Teeri, Lawrence G. Stowe, Darlyne A. Murawski,

Phytochemistry and Biological Activities

The relative abundance of native species in both the Cactaceae and Crassulaceae in different regions of North America is highly negatively correlated with the coefficient of humidity, an estimate of soil moisture content. The species of both families are relatively more abundant in dry habitats as estimated by this coefficient and other moisture variables. The two families exhibit different patterns of seasonal correlation with the monthly values of the coefficient of humidity. The Cactaceae are most strongly correlated with winter values and the Crassulaceae with summer values. The preferred habitats of the Cactaceae are characterized by high rates of evaporation, while the preferred habitats of the Crassulaceae are characterized by low amounts of precipitation. The species of the Cactaceae are much more highly correlated (multiple R = 0.977) with the combination of moisture and temperature variables that best predict their relative geographic abundance than are those of the Crassulaceae (multiple R = 0.888) with the combination of variables yielding the best prediction of their abundance. It is suggested that the expression of the crassulacean acid metabolism (CAM) phenotype may be of less overall importance to the members of the Crassulaceae of North America than it is to the members of the Cactaceae.