| Urban green space is the basic element of the city natural environment. It plays an important role to maintain and improve the urban ecological environment. In this paper, the landscape images 1:2000 were gathered from Google Earth satellite images of Central Districts of Chongqing. Based on the features of urban green space in Chongqing and the classification system, the urban green space in Central Districts of Chongqing was divided into six types, namely park green space, subsidiary green space, residence green space, road and riverside green space, production green space and others. Using AutoCAD, R2V, Fragstats and GIS, some green indexes such as area and coverage of green space in Central Districts of Chongqing were analyzed. The landscape structure was also comprehensively analyzed with some Index, such as size, shape, density of green patches and diversity, connectivity, Fragmented Index of landscape. The same as forest in Zhongliang, Tongluo mountain and the centre city. It will provide reference for building a harmonious and sustainable development urban green space. At the same time, through the surveys of plants, characteristics of plant composition were studied. It is in favor of plant selection and configuration.The primary conclusions are as follows:1) Virescence level of urban green space: green coverage rate (33.30%) is the middle class. Areas of subsidiary and residence green space had the largest proportion (37.02% and 34.56%) , but park green space was seriously inadequate.2) Landscape structure level of urban green space:①The average area of green patches was 0.5 hm~2, There was a largest number of pathes in subsidiary and residence green space. With proportion of number and area (58.92% and 49.26%) , the medium-size pathes were much more than the large and super large-size pathes (22.11% and 13.30%) , small-size pathes was the least. Nubbly was the main type of patches, the wirelike was the least, area total proportion of nubbly and zonal was about 85%.②Density index (0.67) , fractal dimension (1.31) , aggregation index (0.84) connectivity index (0.86) , connectivity index (3.1) and Shannon's Evenness index (0.84) showed that urban green space was complicated, low aggregation and connectivity landscape. Obvious difference on distribution and area occurred in the 6 types green space. As the strong interference by human being, a high degree of fragmentation was formed, especially in subsidiary and residence green space.3) Landscape structure level of the 6 types green space:①The main was large-size pathes in park green space, and medium-size in subsidiary and residence green space, medium and small-sized in road and riverside green space, medium, large and super large-sized in production green space and others. In addition to road and riverside green space which were wirelike and zonal pathes, all of others were almost nubbly.②Highest density index (4.59) on road and riverside green space, lowest on park and the other green space, production green space followed, and subsidiary and residence green space were in middle.③Except in park green space, as strong interference by human being, a high degree of fragmentation was formed in ever other types of urban green space. But with regular shapes, the structure comparatively simple, and showed lower fractal dimension (<1.4) .④Highest aggregation index (0.85) on subsidiary and residence green space, and highest connectivity index(0.88) on road and riverside green space, as a whole, the aggregation and connectivity index were not reach 0.9,so it needs to be further optimized.⑤Shannon-Wiener index (2.89) on road and riverside green space indicated a lower level, but higher on subsidiary and residence green space(3.64 and 3.71). It should strengthen to build different types of green space, in order to increase the diversity.4) The ecological corridor analysis: The corridor width (26.42m) , density (368.47m/hm~2) and connectivity index (0.892) should be improved by increasing appropriately the number and area of street trees.5 ) Landscape structure level of forest: Forests in Chongqing are distributed in Zhongliang, Tongluo mountain and some woodland patches in centre city. In the 2 mountains, forests with average path area (23.58hm~2) hold a high area proportion (78.53%). Surrounding to the centre city, forests in the 2 mountains are regarded as green barriers. Forest in centre city showed a fewer number of pathes, small size and irregular distribution.6) Characteristics of primary plant composition of urban green space:①With artificial configuration, species richness of park, subsidiary and residence green space were higher than the others. Especially, in the other green space which shows natural vegetation. ?The representative families are primary Magnoliaceae, Lauraceae, Palmae, Ericaceae, Theaceae, Rosaceae, Compositae, Gramineae and etc. The representative genuses are primary Ficus, Magnolia, Cinnamomum, Erythrina, Camellia, Rosa, Rhododendron, Zoysia and etc. The Representative arbors are primary Ficus microcarpa, Ficus virens var. sublanceolate, Cinnamomum parthenoxylon, Platanus'hispanica, Erythrina variegate and etc.The shrubs are primary Rhododendron obtusum, Camellia japonica, Ligustrum sinense, Redrlowered loropetalum and etc. The herbages are primary Reineckia carnea, Sambucus chinensis and etc. The vines are primary Parthenocissus tricuspidata, Bougainvillea glabra, Jasminum mesnyi and etc.7) Characteristics of primary plant composition in the 6 types green space researched spots: There are 104 trees, 153 shrubs, 203 herbages, 20 vines in park green space.Mmuch more flowers are artificially configurated; 80 trees, 113 shrubs, 110 herbages, 15 vines in subsidiary green space and 76 trees, 109shrubs, 103 herbages, 17 vines in residence green space, the same as in park green space, much more flowers and garden plants are artificially configurated there.28 trees, 32 shrubs, 52 herbages, 23 vines in road and riverside green space, in addition to a part of natural riverside green space, artificially configuration is dominant.30 trees, 36 shrubs, 30 herbages, 10 vines in production green space, there are much more herbal crops, but trees, shrubs and vines are fewer.36 trees, 45shrubs, 53 herbages, 14 vines grow in the others and distributed naturally.
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