Study On Composition Of Landscape Plant And Species Richness In Urban Districts Of Chongqing

Landscape plants play a significant role in improving living and habitation environment for human beings, as the important elements of urban green space system, urban biodiversity and ecological landscapes construction. Flora of landscape plants are a major part of city landscape. With the rapid development of city, the studies on flora of landscape plants take more attention and become an important part of the study as to the urban forest, urban biodiversity and urban ecological environment. Therefore, the study of landscape plants'flora provides an important theoretical foundation and theoretical basis for building a beautiful living and comfort environment, urban biodiversity conservation, urban ecological landscape construction and urban landscape greening.Urban vegetation composition, species composition or flora (geographical component, growth form) and variety about species richness of landscape plants under different environments, which were researched.The main research results were as follows:1. The vegetations of urban districts were divided natural vegetation (including semi-natural vegetation) and artificial vegetation. There are thirteen vegetation types group and nineteen vegetation types in natural types (including semi-natural vegetation). They mainly distribute in altitude of 300m-450m of the Jinyun Mountain, Liangshan Mountain, Causeway Mountain, Moon Mountain and other mountain series, as well as some knap and drawdown areas of the two River Basin. The natural types(including semi-natural vegetation) mainly form by evergreen coniferous forest, evergreen broadleaf forest, evergreen and deciduous broad-leaved forest, bamboo forest and broad-leaved shrub of forest vegetation and shrub vegetation, including Lauraceae, Theaceae, Fagaceae, Poaceae, Symplocos, Rosaceae, Moraceae and other plant families as component species. Artificial vegetations are composed of the crop vegetation, urban landscape, economic forest vegetation and ecological forest vegetation, distributing in the urban built-up areas, hilly farming areas, town streets and roads, containing Lauraceae, Moraceae, Oleaceae, Ginkgoaceae, Gramineae, Magnoliaceae, Rosaceae and other families'plants.2. There are many landscape plants in the main urban district of Chongqing City, including 198 families, 805 genetics,1985 species totally (including the units under species). The compositions of the subjects mainly are fewer-species families and single-specie family, as large families and large families taking some degree in it. In the composition of species, single-species genetic has a advantage, and some large genetics such as Ficus, Primula are taken part in. In the geographical distribution of the subjects types, tropical and subtropical properties get the absolutely advantage, and the family of global distribution and temperate properties take some proportion, specific components are fewer. 3. Native plants are dominated by woody plants with respect to composition of species. Exotic plants are mainly made up of herbaceous plants, sharing certain components on composition of species. In the geographical components, native plants are dominated by tropical properties; temperate properties next, other components are fewer.4. The low mountain habitat of species are at most, but agricultural and farmland habitats are minimum under different habitats. The dominant species are highest in riparian zone of urban districts and they are the lowest in the habitat of drawdown area. To species richness index, riparian zone of urban districts are highest, low mountains and steep slopes and cliff habitats followed, agricultural and farmland habitats are minimum. Under different types of green space, green types of scenic spots are most, but square greenbelts at the minimum. The numbers of dominant species in scenic spots are highest, but overpass bridges greenbelts'at the minimum. To species richness index, greenbelts of park and scenic spots are highest, but square greenbelts at the minimum. Under different land use types, forest types has the largest number of species, but farmland type are at opposite. The dominant species in farmland types are at most, but water type at least. To species richness index, to the gardening types are highest, but farmland type are at opposite.The number of plant species increase progressively from central urban districts to suburb in central urban districts, transition zone and suburb,with species richness index descending. Landscape plants are mainly woody plants. And the numbers of plant species in Beibei District are most, while they are least in central urban districts. Wild plants are mainly perennial herbs. And the numbers of plant species of Beibei District in suburb are most, while they are least in Jiulongpo zone belonged to transition zone. Abundance index is highest in central urban districts, with minimum in central urban districts. And abundance index of landscape plants in Beibei District are most, while they are least in central urban districts. Abundance indexes of wild plants are highest in Yuzhong District, Coast Region, and Shapingba District, with lowest in Beibei District.