Zonation and establishment of vegetation in selected uninhabited Egyptian and Sudanese oases

Abstract Flora and vegetation of uninhabited Egyptian and Sudanese oases have been surveyed to obtain more knowledge about their groundwater-dependence, distribution and establishment. Similarities in the floristic composition and distribution pattern are assumed to be dependent on the gradients of salt-contents in soil, depth of groundwater table and additionally on salt-tolerance, reproduction behaviour and development of different root systems of the taxa concerned. The vegetative reproduction has an essential function for the preservation of the oases vegetation. Under extreme arid conditions the generative reproduction takes place after sufficient rainfall. Germination and stable establishment of species on the outer margin of the oases need a larger amount of rainfall than the vegetation in the centre.