effect of soil topography on vegetation and structure [phytosociology] of plant communities

ABSTRACT

The study aims at analyzing the vegetation patterns and structure [phytosociology] of Dipterygium glaucum Decne.[Capparidaceae] community, directly after the rainy season. This species is a well known medicinal plant with economic potentialities as well as being a rangeland species, especially in the arid and semi-arid belts along Asia and Africa. It was also recorded in Australia [Richincer, 1969]. The instance of Dipterygium glaucum as one of the famous rangeland species makes it in danger. Its paramount importance as a sand dune-forming species encourages its preferential cultivation along the sides of highways as a shielding dust shelter in windy places.The study was undertaken in the Western region of Saudi Arabia at Ash Shumaysi [45 km from Jeddah] along Jeddah-Mecca road. The study area comprised three transects in three different localities [500 m apart], so that the former was nearer to the motor road while the latter was deeper inside the desert. Soil of the study area was of the sandy type. It was evident that the number of the corresponding species was higher along transect [1] and diminished on going deeper in desert. The most sound result was that Dipterygium glaucum had the highest importance value in its communities, followed by Pennisetum purpureum and then by Citrullus colocynthis