The Relationship Between Vegetation Characteristics And Arid Environment

The Ammopiptanthus communities is a kind of desert community which consists of A.mongolicus and A.nanus as the dominant species. Both A. mongolicus and A.nanus are the only evergreen broadleaf shrub plants in northwest desert region of China. They are the tertiary relict plant, also the China’s focus on the protection of rare and endangered plants. It has important scientific significance and application value for the study on Ammopiptanthus communities.The research object of this thesis are A. mongolicus and A.nanus. The experimental sites are located in Alashan Left Banner, Inner Mongolia and Wuqia County, Xinjiang. The species composition, life form, ecotype, density, coverage of Ammopiptanthus communities are investigated using a sample plot method in filed. By statistical analysis, the main research results are presented as follows:Through the composition contrast analysis of two communities, the results showed that there were 14 families and 47 genera and 50 species of A. mongolicus community, in which the species numbers of Chenopodiaceae, Zygophyllaceae, Gramineae, Leguminosae, Compositae Plants were higher. There were 36 species,33 genera and 16 families of A. nanus community, in which the species numbers of Asteraceae, Chenopodiaceae, Leguminosae Plants were higher.The main geographical elements are the world distribution in the flora of the two Ammopiptanthus community at the family level. The certain difference of minor components existed. the geographical elements of the two community exist certain differences at the genus level, mainly with north temperate distribution, the mediterranean region, West and Central Asian distribution.The vertical structure of two Ammopiptanthus community was divided to the shrub layer and herb layer, in which the synusia development of shrubs and semi shrubs was very obvious, became the main advantage layer of the community. The analysis of plant life form spectra showed that there were mainly the hemicryptophyte and therophyte in the community of A. mongolicus, the hemicryptophyte in the community of A. nanus.The species diversity analysis of two community showed that species diversity of A. mongolicus community was higher than that of A.nanus community. Through the comparison of Shannon Wiener index, Simpson index and homogeneity index, the results showed the diversity index of species in A. mongolicus community is also higher.The composition and structure of Ammopiptanthus community were affected comprehensively by climate, soil, the elevation and other environmental factors. The annual precipitation and seasonal distribution of precipitation was the main environmental factors affecting the composition and structure of Ammopiptanthus community.Both A. mongolicus and A.nanus are facing the threat of the population decline, distribution area reduced. This is because of the arid environment and climate warming are increased, and grazing and other human activities are enhanced. It should further strengthen for the protection and management of Ammopiptanthus community.