Study Of Plant Species Andcommunity Diversity In Xilingol League

Plants specimen collection and community investigation were executed from2010to2011. We consided silinhol league as independent plant flora unit. Though the study on cascular plants diversity, community diversity and the law of communities’ distribution along with hydrothermal gradient, we conclude as follow:(1)There are1242kinds of vascular plants, belongs to415genuses and95families in xilinhol league. New recording species includes1family,5genuses and36species in xilingol league.(2) The vascular plants in silinhol league can be subdivided into7life forms and the proporation as follows:arbor (2.42%), shrub (8.05%), subshrub (2.42%), perennialherb (69.16%), yearly or biyearly herb (17.31%), liana (0.56%) and ephemeroid plant (0.08%). The water ecotypes of plants include mesophyte (mesic xerophyte, mesophyte and wet mesophyte), xerophytism (desert xeric, xerophytism and mid-xeric), humidogene and aquatic.Mesophyte plants and xerophytism plants account for the proportion of65.46%and26.73%respectively.(3)The composition of Floristic geography of tracheophytes is complex and diverse. The Distribution typeof family and genus demonstrate consistency, the predominant Cosmopolitan (57.89%in the number of total subjects,16.87%in the number ofthe total genera) and temperate elements (30.53%in the number of total subjects,62.41%in the number ofthe total genera) play a dominant role. The temperate elements in the geographic composition of the species play a dominant role and it accounted for52.09%, Steppacomposition follews and accounted for20.93%, and then east asian ingredients accounts for the third and it accounted for18.52%。(4)The similarity analysis of vascular plants flora in different steppasubzone of inner mogolia shows that:middle temperature typical steppazone of xilinguole have high similarity with middle temperature desert grass zone of Wulanchabu, warm temperature steppazone of Erdos and middle warm forest steppe of Hulanbeier. The similarity coefficients of family are72.62%,92.86%and92.86%. The similarity coefficients of genera are47.12%,58%and75.75%. The plant floras of those steppacommunities have close genetic relationship in origin and evolution, this phenomenon reflict the consistency of temperate steppaplant flora. But the degree of similarity shows the downward trend with the degree of family-genus-species. This indicates that there is a certain degree of fractionation between different regions of steppe communities. For example, the steppe of Ordos, which is warm temperate grasslands, is mainly composed of thermophilous plant specie; It forms a temperature gradient fractionation with the middle temperate typical steppe Of Xilingol. Floristic composition of Desert steppain Ulanqab is relatively poor and its specific species and category has Low similarity with Xinlingol steppa’s and they have formed a moisture gradient on the differentiation. (5)Here were highly significant correlation between a diversity index, primary productivity and hydro-thermal factors, moisture in Steppe Community of xilinguole league.a diversity index and primary productivity was positively correlated with moisture and precipitation had been showed, namely that there was a decreasing trend from Northeast to Southwest; While a diversity index and primary productivity was negatively correlated with temperature.It namely that there was a increasing trend from Northeast to Southwest with temperature. It also shows that there was a decreasing trend from east to west with species richness and primary productivity.(6)There was a decreasing trend from Northeast to Southwest with mean annual precipitation and there was an increasing trend from Northeast to Southwest with annual mean temperature in xilinguole league.The change law of moisture was basically identical with mean annual precipitation. Grassland vegetation type distribution from east to west, followed by forest, meadow steppe, typical steppe and desert steppe in the area, it phase matched with spatial distribution of moisture. But with the temperatures rise, moisture reduce, the expand of gravelly, salinization habitats and the ancient lake basin in Xilingol League, fragment of Stipa klemenzii community be depth distributed to Xilinhot city and Dongwuzhumuqin country which are typical steppe zone, the eastern section can be reach the coast of herlen in Hulunbeier, so as Allium polyrhizum community and Reaumuria soongorica community.