崖壁是独特生态系统，它险恶的条件使它与其他生态系统产生了隔离，因此在崖壁上生长着一些古老、珍稀的植物。为了适应恶劣的生存环境，崖壁植物对不利生长的生态因子耐受性较强。崖壁生境立面高、坡度陡导致其调查难度较大，因此崖壁生境往往被学者忽略。北京西部山区由于地脉运动以及人为地开山修路、矿石开采等活动形成了大量的崖壁，在此地区还未有学者对崖壁植物进行系统的研究。因此研究北京西部山区崖壁维管植物的多样性及分布特征对于补充北京西部山区崖壁维管植物的研究以及对于人类活动造成的裸露崖壁的恢复有重要的意义。本实验采用样方法对北京西部山区的崖壁维管植物进行了系统的调查，依据《中国植被志》的植被分类体系对北京西部山区崖壁植物进行群落类型的划分。利用Excel软件对152个样方内崖壁植物物种的种类及多度进行统计，同时通过分析Marglaf、Pielou、Simpson三个多样性指数，探究崖壁维管植物在不同海拔、光照、人为干扰等因子下的多样性变化。本研究共记录到崖壁植物78种，属于32科，62属。研究发现崖壁植物在100 ~200 m阶段与600 m以上阶段物种的多样性指数都较高，崖壁植物多样性随着海拔变化不明显。崖壁植物的多样性在阴坡及半阴坡较高，在阳坡植物分布最少。轻微的人类活动会使物种种类变多，丰富度上升，但是强烈的干扰会使崖壁植物难以生长。

The cliff is a unique ecosystem. Its sinister conditions isolate it from other ecosystems, so some ancient and rare plants grow on the cliff. In order to adapt to the harsh living environment, cliff plants have strong tolerance to adverse ecological factors. The high elevation and steep slope of the cliff habitat make it difficult to investigate, so the cliff habitat is often ignored by scholars. In the western mountainous area of Beijing, a large number of cliffs have been formed due to the movement of ground veins, artificial mountain construction, ore mining and other activities. Therefore, it is of great significance to study the diversity and distribution characteristics of vascular plants in the cliffs of the western mountainous areas of Beijing to supplement the study of vascular plants in the cliffs of the western mountainous areas of Beijing and to restore the bare cliffs caused by human activities. In this experiment, the vascular plants of cliffs in the western mountainous areas of Beijing were systematically investigated by sampling method. According to the vegetation classification system of ' Chinese Vegetation ', the community types of cliff plants in the western mountainous areas of Beijing were divided. Excel software was used to count the species and abundance of cliff plants in 152 quadrats. At the same time, by analyzing the three diversity indexes of Marglaf, Pielou and Simpson, the diversity changes of cliff vascular plants under different altitudes, light and human disturbance were explored. In this study, a total of 78 species of cliff plants were recorded, belonging to 32 families and 62 genera. It was found that the species diversity index of cliff plants was higher in the 100 ~ 200 m stage and above 600 m stage, and the diversity of cliff plants did not change significantly with altitude. The diversity of cliff plants is higher on shady and semi-shady slopes, and the distribution of plants on sunny slopes is the least. Slight human activities will increase species diversity and richness, but strong interference will make cliff plants difficult to grow.