Studies On Distribution Of Alien Species And Influential Factors In Beijing

As an international metropolis, Beijing has been developed rapidly in recent years. With the economic development, the number of invasive species become faster and faster. In order to protect native plants, and to realize distribution of plants in Beijing, we investigated twelve districts and counties, most of them are woodland and farmland. Based on a comprehensive survey for vegetations in Beijing, the community structures, types of community and the composition and distribution of species, plant communities were studied. Based on the field investigation and data analysis, the main results as follow:(1) 1524 species has been listed in Beijing, which belongs to 626 genera,141families, including 234 cultivated plant,1290 wild plant. Most of the species are herbage, and most of it belong to the family of Compositae, Papilionaceae, Gramineae, Rosaceae. The number of species in Mentougou, have is most in Beijing, and 1078 species were listed.(2) 234 alien plants has been listed, which belongs to 165 genera,72families. Composite, Papilionaceae and Rosaceae have more species than other ones.67.77%alien plants were introduced from Asia. The world distribution plants account for 51.07%. And ornamental plants occupy 28.22%. World distribution and South temperate distribution of genera is dominate.(3) 28 invasive alien species has been listed. Composite, Papilionaceae and Rosaceae have more species than other families. All of the species are herbage.18 invasive alien plants were introduced from America. Meanwhile, the dispersal of invasive plants is different at each counties or districts. The number of invasive species is the most in Tongzhou, is 18 species, and the least in Haidian, is only 1 species.(4) The influentialfactors on distribution are divisional factor, economical factor, forest area factor, farm factor and protected area. We used the influential factor to classify all the districts and counties into 4 groups; Shunyi, Tongzhou, Daxing and Fengtai are in one group.Haidian and Pinggu are in groups.Changping, Fangshan, Huairou, Miyun, Mentougou and Yanqing are in one group. The number of visitors and GDP have decisive effect on distribution of plants.