The Study Of Plant Diversity Of Green Space In Urban Built-up Area Of Guangzhou City

With the increase of urban population, the rapid development of economy and the expanding of urban area, urban ecological environment are more and more affected by human activities, resulting in deterioration of urban ecological environment and urban biodiversity reduction. Finally, have a negative impact on the urban living environment and sustainable urban development. According to the green space type and area size, we determined the sampling volume, and the amount of arbor, shrub and herb to determine the sampling proportion. And then through the computer and remote sensing image to select different levels of sampling point, a total of136sample points were selected. In this study, we adopted the method of stratified random sampling to in vestigate the plants of all types of green space and spatial distribution in urban built-up area of Guangzhou city. We studied the built-up area of plant species composition features, including chorology, origin, life form, importance value and ecological system diversity. Comparative analysis the different type of the plant species composition and distribution, and discuss the exotic plants and invasive plants in the compositional characteristics of the different types of green space. Finally, according to the research results, this paper put forward the city biodiversity conservation measures and suggestions of the built-up area in Guangzhou. The results of the study were as follows:(1) There were rich plant resources of green space in urban built-up area of Guangzhou city. A total of572plant species belonging to386genera and123families (including varieties) were concerned, including33invasive species. Arboreal58families,145genera and214species. Shrubs31families,67genera and107species.Herbaceous plants was the most abundant, a total of61families and171genera and228species. The vine15families,19genera and23species. There were rich plant resources in Guangzhou, but imbalanced in the distribution of the type of life. So, we should increase the application of shrubs and vines to creat the rich layers of plant communities.(2) According to families statistics, there were13families of ferns,9families belonging to pan-tropical distribution. There were109families of seed plants. World distribution,24 families. Tropical distribution,67families. Temperate distribution,18families. Genus statistics, fems14genera divided into five areal types. Seed plants372genera, among them world distribution18genera, tropical distribution281genera, temperate distribution53genera. Endemic to East Asia and China20genera. Through different green space type system clustering analysis we found that floristic structure was most similar among road affiliated green space, public affiliated green space and protective green space. City street green space and residential green space and community park were similar. Industrial affiliated green space and wasteland the areal types were similar.(3) Dominant plants structure:The dominant speices tree of green space in urban built-up area of Guangzhou city were Ficus microcarpa,Ficus altissima, Ficus benjamina,Bombax malabaricum,Michelia alba.The dominant speices in the shrub layer were Duranta erect a, Sehefflera arboricola, Excoecaria cochinchinensis, Fagraea ceilanica, Ficus microcarpa. The dominant plants in herb layer were Zoysia japonica, Cynodon dactylon, Axonopus compressus, Syngonium podophyllum,Zoysia tenuifolia..The dominant families were Gramineae, Sankoh, Palm, Euphorbiaceae, Araliaceae, etc. The dominant genera were Zoysia, Ficus, Sehefflera, Cynodondactylon, Duranta, etc.(4) Similarity of green space plants:The highest similarity degree was industrial subsidiary green land and wasteland species, the second was public services subsidiary affiliated green space and road green space, comprehensive theme park and other types of green park had a significant difference. In the tree layer, the highest species similarity was between comprehensive theme park and community park plant, a total of44species of the same plants. In the shrub layer, the highest species similarity was between residential affiliated green space and comprehensive theme park, a total of39species of the same plants. In the herb layer, the species of road affiliated green space, street green space and comprehensive theme park, community park was similar.(5) About plant diversity:The Margalef diversity index and the number sequence of different life forms both showed up as herb layer> tree layer> shrub layer in urban built-up area of Guangzhou city. The Margalef diversity index of the tree layer was27.64, the shrub layer was 13.76, and the herb layer was29.46. Shannon Wiener and Simpson diversity index was tree layer> shrub layer> herb layer, The Shannon Wiener diversity index of tree layer was4.21, the shrub layer was3.47, the herb layer was1.61. The Simpson diversity index of the tree layer was0.98, the shrub layer was0.94, the herb layer was0.63. Pielou evenness index of the tree layer and the shrub layer were similar, tree layer> shrub layer> herb layer. The tree layer evenness index was0.79, the shrub layer evenness index was0.74, the herb layer evenness was0.3.In the nine types of green space, Comprehensive theme park had the highest plant richness,Community park took the second place,Wasteland the lowest. The highest Simpson diversity was public service affiliated green space, and then residential affiliated green space, the lowest was industrial affiliated green space and wasteland. The highest Shannon-Wiener diversity was comprehensive theme park, the second was affiliated residential green space,the lowest was industrial affiliated green space and wasteland. Service affiliated green space had the highest Pielou evenness index,the second one was industrial affiliated green space, Wasteland the lowest.(6) Exotic plant structure:Native plants were used inadequate and exotic plants had large proportion in the green space of Guangzhou urban built-up area.213species of alien invasive plants belonging to162genera of62families,37.24%of the total. Including trees78species, shrubs43species, herbs43species, vine5species.35kinds of invasive plants,9alien invasive species were evaluated to be at the highest degree of threat to the local biodiversity,14at the medium,and12at the lowest.The species which had caused serious threat were Alternanthera philoxeroides、Mikania micrantha、Eupatorium catarium、Wedelia trilobata、 Bidens pilosa、Aster subulatus、Mimosa bimucronata、Lantana camara. Alien plants in pan tropical and tropical Asia and tropical America discontinuously distributed components of plant had the highest percentage, native to tropical America alien plants occupied obvious advantages.