Contribution to the study phytoecological of facies Pistacia atlantica Desf. in the Saharan Atlas (Béchar-Algeria)

The atlas pistachio (pistacia atlantica desf.) is a very common in southern algeria native species. phytoecological a study group to pistacia shows a perfect adaptation to soil and climatic environmental conditions predominate in the oranian saharan atlas (bechar). the pistachio atlas is a very hardy tree scrublands,with a very large amplitude bioclimatic where it currently appears between 0 and 3.7°c on altitudes between 700 and 1200m,this coincides with the levels of vegetation meso and thermo-mediterranean in the south,the slopes and cliffs of the saharan atlas. this essence merely a low rainfall of about 100 mm/year and sometimes less; this explains the amount of water low water levels of different indices. despite its great ecological and economic values,pistachio atlas region is in a critical situation due to drought exacerbated by one year to another,its uncontrolled exploitation for firewood and fodder by population,and because of its grazing,preventing natural regeneration. a better understanding of the issues and factors in the decline of pistacia atlantica contributes to the protection of biodiversity and better regeneration and expansion of this species in semi-arid areas.