Etude phytosociologique et pastorale des djebels Youssef et Zdimm (Hautes plaines Sétifiènnes)

Abstract

Flora and vegetation of djebel Zdimm and Youssef (Setif High Plains) have not been any scientific study. Have privileged framework and exceptional biological context , this study seems to us necessary.Prospections that we have undertaken prouved the presence of a relatively rich and varied flora.we have defined two main types of Mediterranean ecosystems: ─ the matorral of Pinus halepensis and Quercus ilex ─ Semi-arid steppes occupy large areas in this region. According to plant, three dominant types of steppes are recognized: -Stipa tenacissima and Juniperus phoenicea- Stipa tencissima and Launaea acanthoclada - Artemisia herba alba steppe The phytosociological analysis reveals seven plant communities on both massifs, each with a certain particularity. These groups are attached to three phytosociological classes: - the Lygeo-Stipetea -Quercetea ilicis – Tuberarietea guttatae.The floristic inventory has highlighted 310 taxa distributed between 55 families and 214 genus.The very advanced degradation of vegetation of djebel Youssef and Zdimm is mainly due to anthropozoic action compounded by very stringent climatic conditions, including recurrent periods of droughts. Regression of the vegetation (over 50%) was accompanied by the scarcity of woody and proliferation of therophytes and chamaephytes (thorny and toxic). The abrupt change in vegetation physiognomy on djebels Youssef and Zdimm is worrisome. The vegetation is facing serious degradation and desertification threatened.