North African steppes are subjected to extreme degradation resulting in the reduction of their surface, genetic erosion of resources, and decrease in biodiversity. "Stipa tenacissima" steppes, which constitute one of the most representative vegetation types in the driest areas of the Mediterranean basin, are continuously degrading. With the aim of contributing to a better knowledge of the floristicudcomposition and diagnosing the state of degradation of these steppes, we conducted a phytoecological analysis of 10 "S. tenacissima" sites in Tunisia. Floristic inventory compiled a systematic list of 46 vascular plant species belonging to 43 genera and 26 families. Species richness ranged from 4 to 18 species per 900 m2. Total vegetation cover was moderate and fluctuated between 22.8% and 49.9%.udOur results revealed also a decreasing trend in species richness with increasing elevation (ρ = –0.585). Indeed, species richness was negatively correlated with slope (ρ = –0.19) and positively correlated with sand content (ρ = 0.262). Biological types were dominated by chamaephytes; this chamaephytization is due to the phenomenon of aridization and overgrazing. Moreover, the low species cover and the appearance of nonpalatable species highlighted the vulnerability of these steppes to degradation.
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机译：北非草原极度退化，导致其面积减少，资源遗传侵蚀和生物多样性减少。 “ Stipa tenacissima”草原是地中海盆地最干旱地区最有代表性的植被类型之一，在不断退化。为了更好地了解这些植物的植物区系/分解和诊断这些草原的退化状态，我们对突尼斯的10个“ S. tenacissima”位点进行了植物生态学分析。植物区系清单汇总了属于43属和26个科的46种维管植物物种的系统清单。物种丰富度为每900平方米4至18种。总植被覆盖度适中，在22.8％和49.9％之间波动。实际上，物种丰富度与坡度呈负相关（ρ= –0.19），与沙含量呈正相关（ρ= 0.262）。生物类型主要由生植物组成。这种赘生物化是由于干旱和过度放牧的现象。此外，低种的覆盖率和难吃的物种的出现凸显了这些草原对退化的脆弱性。
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