Abstract Most of the sand dunes close to the Mediterranean coast of Egypt have been destroyed due to human pressures. The remaining dunes are under extreme threat due to unplanned development. This study aims to explore the floristic patterns and detect which drivers threaten their conservation status. Eighty-five random plots of 100 m2 each along 12 transects perpendicular to the seashore in the northwestern coastal dunes were sampled. Classification of plots using plant cover percentage was carried out through agglomerative hierarchical clustering and principal coordinate analysis. Canonical correspondence analysis (CCA) and variance partitioning (VP) were used to define the drivers that influence the floristic patterns. Therophytes and chamaephytes represent 30% of each of the 113 vascular plant species recorded in the present study. Four clusters of plant species corresponding to four dune-types were identified: Ammophila arenaria - Ononis vaginalis in foredunes, Echinops spinosissimus- Launaea fragilis in embryonic dunes, Echinops spinosissimus- Allium erdelii in transitional and Echinops spinosissimus- Thymelaea hirsuta in stabilized dunes. Stabilized dunes showed the highest diversity (species richness Hdune = 1.37, evenness Edune = 0.88) and rarity indices (R = 0.52) as well as a steeper rarefaction curve. CCA disclosed that organic matter and CaCO3 content, distance from the coastline, overcutting, trampling, and urbanization were correlated with the floristic patterns. VP showed that the examined variables justified for 53% of the variance in the floristic composition. Our results can be considered by managers to fulfill an appropriate conservation plan to preserve and manage the coastal dunes in arid regions.

中文翻译：

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埃及地中海沿岸沙丘生态系统的植物区系模式和生态驱动因素

摘要 埃及靠近地中海沿岸的沙丘大多因人为压力而遭到破坏。由于计划外的开发，其余的沙丘正受到极大的威胁。本研究旨在探索植物区系模式并检测哪些驱动因素威胁其保护状态。沿与西北海岸沙丘的海岸垂直的 12 条横断面，随机抽取了 85 个 100 平方米的样地。通过凝聚层次聚类和主坐标分析使用植物覆盖率对地块进行分类。规范对应分析 (CCA) 和方差分区 (VP) 用于定义影响植物区系模式的驱动因素。在本研究中记录的 113 种维管植物物种中，Therophytes 和 chamaephytes 分别占 30%。确定了对应于四种沙丘类型的四组植物物种：Ammophila arenaria - 前沙丘中的 Ononis、胚胎沙丘中的 Echinops spinosissimus-Launaea fragilis、过渡性沙丘中的 Echinops spinosissimus-Allium erdelii 和稳定沙丘中的 Echinops spinosissimus-Thymelaea hirsuta。稳定沙丘显示出最高的多样性（物种丰富度 Hdune = 1.37，均匀度 Edune = 0.88）和稀有指数（R = 0.52）以及更陡峭的稀疏曲线。CCA 揭示有机质和 CaCO3 含量、距海岸线的距离、过度砍伐、践踏和城市化与植物区系模式相关。VP 表明，所检查的变量证明植物区系组成中 53% 的变异是合理的。