Comparaison et phytoécologie des Atriplexaies en Oranie (Algérie)

Abstract

The numerous studies carried out on the halophilous vegetation in Oran region (Algeria) still require complementary contributions. Bioclimatically, the pluviometric gradient decreased from North of Algeria (Messerghine and Béni-Saf) to South (Chott El-Gharbi) which influences the floristic composition of the atriplexaies of the two zones. A pedological study showed sandy loam or a silty loam texture in the majority of the stations of the two zones. In addition, the rate of salinity increased in the South compared to North except the station of Messerghine (near to Oran Sebkha), whereas the organic matter rate was very low in the South. The new element brought by this study to the analyses of biologic diversity, it is that we took into account the relative abundance of species as well as their presence. In the Northern zone, the matorralisation and the anthropisation mark the floristic landscape in Béni-Saf. In Messerghine the floristic composition of Atriplexaies remained halophilous. The floristic procession of Atriplexaies of the Southern zone (Chott El-Gharbi) was marked by low species richness in bond with the overgrazing which probably induces probably a floristic succession to steppes dominated by Peganum harmala between El Aricha and Abdelmoula. CA (Correspondance Analyses) carried out using the software Minitab 12 informed us on the factors governing floristic composition of the atriplexaies of the two zones : for the Northern zone, in Messerghine, the edaphic parameters (moisture, O. M and salinity) mainly explained the information brought by the first two axes (41%). In Béni-Saf, while moving away from Oran Sebkha, the anthropic activities accounted for a great part of information (more than 55%). For the Southern zone, in the station of El Kasdir 01 (steppe field), it was both the edaphic parameter (salinity) and the anthropic factor which explained the information brought by the first two axes (61,1%).