The area of El-Tarf constitutes a remarkable natural environment, for its exceptional biodiversity in the Mediterranean basin. It is ecosystem which proves more to be weakened. Its lakes complex undergoes since years increasing environmental pressure. These banks of the lakes are overgrazing and plowed frequently, which affect certainly the floristic composition and their habitat. Vegetation, natural species and abiotic factors, soil characteristic physicochemical, were evaluated in 66 stations distributed over the lakes, along moisture gradient. 25 native species were founded: Poaceae 48%, trifolium 20%, médicago 16% and 16% other Fabaceae . A long term of disturbance has lead species to response to environmental variables. 3 groups of species were formed sharing the same strategies adaptive and have similar ecological attributes. These functional groups are abundant around the lakes. The results indicate that the floristic composition is homogeneous in the 3 lakes, the soil fertility is low but, did not affect the floristic composition, owing to the fact that the species are tolerate. The moisture gradient did not effect the species distribution. In return, human activity (practices) plays a major role in the 3 lakes since 19th century. The last 20 years, human activity has increased dramatically in this area, which explains the loss of plant diversity and has direct effect reducing the species richness chiefly due to degradation of habitats and reducing seed production and the stock seed in the soil.