Abstract: The West Ordos,which is located in the core region of the Alashan-Ordos biodiversity center,is one of the key areas for biodiversity researches. In recent years, mineral resources are exploited in a large scale, industrial zones are expanding all the time and grazing continuously happens. The impacts of anthropogenic factors lead to a high degree of regional habitat fragmentation. If we take the change in the global climate into consideration , all of the above seriously threat to community diversity. In order to repair the broken habitat and construct a reasonable vegetation cover, we must know more about the composition of the native communities, especially we need to master the difference and relations between different layers of the communities and the desert communities with the neighbors. Here we use the field community investigation method to investigate and analyze 53 plots from 12 plant formations in this region. The results indicate that ① The west Ordos desert vegetation includes a number of mono-type and oligoro-types genera, such as Tetraena mongolica, Helianthemum ordosicum, Ammopiptanthus mongolicus, Potaninia mongolica, Tugarinovia mongolica. They not only increased the diversity of plant communities in West Ordos, but also reflected the uniqueness of plant diversity. ② Shrubs in West Ordos steppe desert, in terms of the composition of the life form spectrum, is 13.1% higher than that of adjacent desert steppe and become constructive or dominant species of communities in different habitats. Most of them are constructive or dominant species in different habitats and sufficiently reflect the feature of steppe desert. ③ By comparison of plant life form spectra between steppification desert and desertification steppe, shrub is 13.1% higher in steppification desert than desertification steppe. In terms of the water ecological type spectrum, the proportion of strong xerophytes is 15.9% higher in the desertification steppe nearby, although typical xerophytes are the dominant plants here. ④ There are many kinds of plant community types in West Ordos steppification desert. Species diversity of typical steppification desert communities (such as Form. Zygophyllum xanthoxylon, Form. Potaninia mongolica, Form. Ammopiptanthus mongolicus, Form. Tetraena mongolica, Form. Helianthemum soongoricum, Form. Artemisia ordosica) has a higher diversity and is of stability due to interactions between the herb layer and shrub layer. ⑤ Compared with desertification steppe, β-diversity is higher in West Ordos steppification desert communities. For this reason, West Ordos steppification desert can accommodate more communities for co-existing together.

Key words: steppification desert, formation, Plant community, species diversity index, West Ordos