The botanical and edaphic inventory investigations of the spontaneous flora distribution in the regions of Ouargla and Ghardaïa revealed the presence of 56 taxa of which 32 were ephemeral and 24 vivacious. The sweeping operation of 6 stations over these two regions showed an abundant richness estimated to 39 species localized mainly in the beds of Wadis and distributed as follows: Reg (19), Sebkha (7), Erg (6) and Hamada (5). The average richness of species was about 4, 83 in the beds of Wadis and 0, 83 in Hamadas. The abundance and dominance of plants varied within the same species from one station to another. In fact, severe climato-edaphic conditions gave rise to isolated life. For example, Chamephytes dominate in dry and moderately humid environments as in the Reg of Hassi Ben Abdellah and Wadi N’sa. However, in humid zones such as the Wadi M’zab, it was therophytes that dominated. In these dry zones, the spontaneous plants were distributed according to their ecological affinities. The position of each species depended on different ecological factors such as dryness, soil and humidity.

 

Key words: Distribution, spontaneous flora, richness, soil, Sahara.