Abstract:On the high plains of Setif, the old inhabitants have built a real knowledge of medicinal plants properties. Traditional knowledge about plants and their properties are still fairly common. Our scientific motivation stems from the absence of any flora and ethnobotanical study in this area. During different field campaigns, we identified 93 medicinal species belonging to 32 botanical families. This number reflects the wealth of medicinal plants that are still traditionally used. To gather as much information on the use of plants, a series of ethnobotanical surveys were conducted in the field during periods of picking from villagers, herbalists and traditional healers. According to those surveyed, the fresh leaves and seeds are considered the most popular and common parts that can address several diseases where oral and dermal administration are recommended. The most used plants are: Artemisia herba-alba, Argyrolobium saharae, Gymnosporia senegalensis, Ormenis africana, Pallenis spinosa, Thymus ciliatus, Pistacia atlantica, Paronychia arabica, Globularia alypum, Ajuga iva, Peganum harmala, Ruta chalepensis, Tapsia garganica, Pituranthos scoparius. Djebel Zdimm offers floristic diversity and a sizeable traditional therapeutic knowledge. The safeguarding and preservation of this ancestral heritage is one of our objectives in this semi-arid steppe.

Djebel Zdimm is a moutain part of the Tellian high plains (plains located between the coastal Tellian Atlas and the inland pre-Saharan Atlas). Its steppe vegetation has never been scientifically studied. Its location in the semi-arid Tellian high plains gives it a particular character in a territory mainly devoted to cereal cultivation. This mountain is mainly used for grazing. Having a privileged physiognomic setting and exceptional biological context with 243 species, a detailed study was therefore necessary. The inventory of the natural vegetation was carried out to characterize it physiognomically and syntaxonomically while highlighting the importance of environmental conditions and human impacts on vegetation dynamics. This diachronic study demonstrated a trend towards a significant qualitative and quantitative regression of vegetation cover, which decreased by 80% in the most degraded areas. Under the effect of the strong anthropic pressure and climatic hazards, the composition of the steppe vegetation has changed. Species indicating some kind of degradation were : Astragalus armatus, Atractylis serratuloides, Deverra scoparia, Erodium glaucophyllum, Hammada scoparia, Peganum harmala, Tetraena simplex, Thymelaea microphylla.

Dans les hautes plaines setifiennes, la roche calcaire, composante principale de Djebel Zdimm, a contribué à l’installation d’une végétation lichénique saxicole très diversifiée et qui présente un très grand intérêt biologique et phytogéographique, en raison de sa présence dans une steppe semi-aride avec une saison sèche prolongée sur plus de cinq mois. L’élaboration d’une première liste de lichens pour Djebel Zdimm nous a permis de recenser 55 espèces saxicoles identifiées et signalées pour la première fois dans un écosystème steppique dont 5 sont nouveaux pour l’Algérie : Acarospora nitrophila H. Magn., Myriolecis invadens (H. Magn.) Śliwa, Zhao Xin et Lumbsch, Melanelia stygia (L.) Essl, Squamarina concrescens (Müll. Arg.) Poelt et Verrucaria sphaerospora Anzi. Cette étude participe non seulement à compléter les connaissances lacunaires sur la flore lichénique de l’Algérie, mais aussi à la conservation et la protection de la diversité biologique de cet écosystème steppique face aux changements climatiques.

Regressive dynamics of vegetation of Setif high plains : erosion of plant diversity in djebel Youssef (Algeria). The extensive degradation of the vegetation of djebel Youssef (Setif High Plains) is mainly due to the anthropozoic action, worsened by very constraining climatic conditions, including recurrent periods of droughts. The flora and vegetation of this mountain had not been previously studied. Surveys that we have undertaken show the presence of a relatively rich and varied flora. To follow the evolution of the flora and vegetation, we conducted a diachronic study of 10 years. Results presented in this paper are the first observations for the decade 2000-2010. Regression of vegetation was accompanied by depletion of phanerophytes and proliferation of therophytes. At a very advanced dematorralization already succeeded a steppe, resulting from an extensive therophytization highlighted by the analysis of biological spectra. The flora is thus constituted by 70 % therophytes and marked by the scarcity of phanerophytes (7 %). The relative importance of desert species (over 12 % of the saharan-arabic species), indicates the progressive aridity of the region.

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