Study on Geographical Flora of Landscape Plants and Application of Exotic Species in Wetland Parks of Dianchi Lake

From 2017 to 2019, 17 wetland parks of Dianchi Lake were investigated 4 times by using the method of combining field route survey and key census. The species composition, diversity, geographical flora, application of exotic species and species with invasion history of landscape plant were systematically studied, and the similarity of landscape plant in various parks was analyzed. The results indicate that in there are totally 338 species of landscape plants in Dianchi Lake, including 13 varieties, 4 forma, 3 hybrids, 11 varieties cultivar, and 4 cultivates. The main life form includes arbors, shrubs and perennial herbs. In family, there are 20 families including more than 5 dominant families, while in genus, there are 222 genera with 1-5 species, indicating that wetland of Dianchi Lake has rich diversity of landscape plants. There are 11 types and 9 forma of the section-level geographical distribution types of landscape seed plants. In addition to the world-wide distribution, the proportion of tropical distribution is large, with R/T value in family being 1.92, which has a distinctly tropical characteristic. There are 14 types and 15 forma of the genus distribution, with 46.40% tropical components and 47.30% temperate components separately, R/T value in genus being 0.98, which shows that the genus of landscape plants around Dianchi Lake is mainly composed of temperate geographical components, but tropical geographical components also account for a large proportion. The number of exotic landscape plants and landscape plants with invasion history is large, 132 species of 99 genera in 43 families, and 51 species of 45 genera in 28 families, most of which are native to South and North America. Application rate of exotic landscape plants in each park is varied from 30% to 50%, which shows that the application of exotic landscape plants in wetland parks of Dianchi Lake is universal, and the number of exotic species in some parks is basically equal to that of local species. The similarity coefficient of the landscape plants in all wetland parks of Dianchi Lake, is between 0.3 and 0.57, among which 9 wetland parks have a similarity of more than 50%. It shows that the landscape plants in the wetland parks of Dianchi Lake still have a high similarity, under the condition of using a large number of exotic landscape plants, and the heterogeneity of exotic plants to the landscape is not obvious.