Abstract
THE PRESENT study aims at evaluating the state of Calotropis procera to adapt to different environmental conditions and identifying the patterns and sizes in terms of dimensions, size structure and density. Seventy five stands were selected in Taif region and its adjacent area to represent the environmental variations associated with the distribution of C. procera. The population structure of this species was evaluated in terms of size distribution. All dimensions of C. procera differed significantly along the altitude gradient, habitat and locations, except that of diameter which did not differ significantly along the altitude gradient and habitats. The altitude of 1300-1500m above sea level had the maximum values of height, size index, volume and height: diameter ratio, while the altitude of 1500-1700 had the minimum of height, diameter, and size index. Regarding habitat types, wadi beds had the maximum values of diameter, size index and volume, while depression spots had the maximum of height and height:diameter ratio. Sand flats had the minimum values of all population dimension. The density of C. procera differed significantly along altitude gradients. The total mean of size index-class frequency distributions of C. procera population approximated the positive inverse J-shape in the study area towards the relative preponderance of small individuals.