Abstract:

Grassland is one of the most important vegetation types on the Loess Plateau.Howeever the relationship between the Loess Platean and the Eurasion steppe has not yet been elucidted. In this study, the seed plant flora of the Loess Plateau was used as a single research object for the first time. On the basis of the field vegetation survey and a large number of references, a seed plant flora list of grassland plants in the Loess Plateau was established. Based on the theories and methods of geobotany, study of plant flora composition, life type, water ecotype, floristic character, endemic phenomenon, geographical composition and geographical relations are carried out. The seed plant flora of grassland in the Loess Plateau and Inner Mongolia plateau is compared and analyzed. The main results are as follows:The basic characteristics of the grassland flora in the Loess Plateau are clarified; the species similarity of the seed plant flora on the Loess Plateau and the Inner Mongolia plateau grassland is relatively high on family and genus level, not on species level. There are significantly differences in the geographical compositions between Loess Plateau steppe and Inner Mongolia plateau steppe; the most important difference is that the seed plant flora of the Loess Plateau steppe is closely related with that of the Northeast China. East Asian components occupy a more important position in the seed plant flora of the Loess Plateau steppe; the vertical zonal geography play an important role in the formation of the loess plateau steppe.

Key words: Loess Plateau, Grassland vegetation, Seed plant flora, Geographical elements, Geobotany

摘要：

黄土高原草原是中国北方温带草原带的重要组成部分，但黄土高原草原与欧亚地带性草原的关系尚未阐明。本研究将黄土高原地带性草原种子植物区系作为单独的研究对象，建立了黄土高原草原种子植物名录，采用植物地理学的相关理论与方法，对黄土高原草原和内蒙古高原草原植物区系的相似性和地理成分进行了系统的比较分析。结果表明：黄土高原草原与内蒙古高原草原种子植物区系在科属水平上的区系相似度较高，但种水平的区系相似性较低。区系的地理成分有较大差异，且最主要的差异在于黄土高原草原植物区系中东亚成分具有更重要的地位。垂直地带性对黄土高原草原的形成有重要作用，适宜草原发生的环境条件使得黄土高原表现出大面积的温带草原景观，但黄土高原草原应区别于欧亚草原的地带性植被。

关键词: 黄土高原, 草原植被, 植物区系, 地理成分, 植物地理学