CONTRIBUTION A L’ETUDE DES ATRIPLEXAIES EN ALGERIE OCCIDENTALE, ASPECTS PHYSIONOMIQUES ET PHYTODYNAMIQUES

The increasing interest groups in Atriplex halimus (Atriplexaies), prompted us to make our contribution through the present work. After an examination of the physical environment of our study area is part of Oran, the bioclimatic study revealed a rainfall gradient which decreases from north to south. The floristic study has highlighted the diversity of our Atriplexaies, this was confirmed by the correspondence analysis performed using Minitab 15. At the station Messerghine, soil parameters (moisture, organic matter and salinity) account for much of the information provided by the first two axes (41%). At Beni Saf, away from the Sebkha Oran, the human factor explains much of the information (55%). For the station of El Kasdir (steppe area), is both the edaphic parameter (salinity) and especially the parameter that explain human information provided by the first two axes (61.13%). Our work also includes an overview on the dynamics of halophyte steppe regressive, it is a diachronic study conducted on the station Hassi Mellah from floristic surveys conducted in 1991 and 2005. In the end a chapter was devoted to mapping, it is design physiognomic five windows (three north and two south) which helped to illustrate the features and the heterogeneity of plant formations and more particularly stands halophytes. We note that the settlements pure Atriplex halimus present cover only 3% of the total area in the five windows. The agricultural areas dominate the window of El Malah (64.69%), while lawns and structures matorrals occupy over 50% of the surface of Emir Abdelkader windows and Zenata. Peganum harmala Atriplexaies invaded the Chott El Gharbi, scoring his presence, his dominance instead of 50% of the total area of windows in this area. Keywords: Atriplexaies, correspondence analysis, vegetation dynamics, vegetation mapping, north of Tlemcen,Chott-El-Gharbi, Oranie (Algéria