Research On The Characteristics Of Plant Communities Of City Street Greenbelt And Landscape Evaluation

Based on the investigation and analysis of the current situation and structure of street greenbelt's plant community of West Lake distract in Hangzhou city, combine with the ecology and landscape architecture and breaking through the single study of city greenbelt, serves as the basis of improving the plant application of city greenbelt, optimizing the current structure of plant community of urban street greenbelt, building urban greenbelt with healthy ecology, beautiful landscape and sustainable development, meanwhile it provides the relevantly referential suggestions to build the urban street greenbelt, which has some theoretical meaning. The street greenbelt's plant community of the region of West Lake in Hangzhou city as the research object, the study involves 15 arteries and 55 respective sample areas are chosen to comparatively study the plant composition of plant community, the species diversity, the landscape quality and ecological effect and so on. Also the further optimizing suggestions of current plant community of urban street greenbelt are put forward. The main conclusions are as follows:(1) Among the 55 typically investigated plant communities of street greenbelt of West Lake region in Hangzhou city, trees are belonged to 23 families, 33 genera and 47 species; shrubs are belonged to 24 families, 30 genera and 40 species; herbaceous plants are belonged to 13 families,24 genera, 26 species, totally amounting to 52 families, 84 genera, 113 species and respectively accounting to 22.5% in family, 6.1% in genus, 2.9% in species of current plants in Zhejiang province, in which Gymnospermae are belonged to 5 families, 7 genera, 10 species and Angiosperm are belonged to 47 families, 77 genera, 103 species.(2) The types of man-made plant community of street greenbelt of West Lake region in Hangzhou city having zonality. Evergreen defoliate broad-leaved mixed forest is dominated and its distribution reaches up to more than 43.6% and the evergreen broad-leaved forest and conifer and broadleaf mixed forest are following, accounting to 25.5% and 23.6% respectively, while the distribution of defoliate broad-leaved forest is lowest, only 7.3%. It can be seen that the evergreen defoliate broad-leaved mixed forest, with evergreen tree species oriented, dominates in the vegetation types of man-made plant community of street greenbelt of West Lake region in Hangzhou city.(3) In the sample areas, the tree in the highest emergence frequency among 47 tree species is Cinnamomum camphora ( the frenquency is 49%) and the following are Opsmanthus fragrans, Acer palmatum, Ginkgo biloba, Elaeocarpus glabripetalus etc. The shrub in the highest emergence frequency among 40 shrubs is Loropetalum chinense (the frenquency is about 32%), and the following are Photinia serrulata, Pittosporum tobira, Camellia japonica, Ilex cornuta var. fortuneietc. The species abundance degree of tree, shrub and grass layers in different types of plant community are significantly different.(4) The plant community structure of the investigated street greenbelt is mainly the complex community with tree, shrub and grass. From the comparison of each species richness of tree, shrub and grass of the plant community's different forest types of the investigated 55 sample areas, in tree layer, the tree species of conifer and broadleaf mixed forest are richest, while the average species per unit area of the evergreen broadleaf type are lowest. According to the species richness in tree layer, the forest types are: conifer and broadleaf mixed type>evergreen defoliate broad-leaved mixed type>deciduous broadleaf type>evergreen broadleaf type.(5) The average species richness index of trees, shrub and grass in the 55 surveyed plant communities is 2.5697. The average Gleason species richness index is 0.4890, The average Margalef species richness index is 0.4340, The average Simpson index in ecological dominance is 0.3076, The average Shannon-Wienner index is 0.6446, The average Berger-Parker index in ecological dominance of dominant species is 0.6869.The richness and diversity index of plant communities are calculated according to the survey data of street greenbelts sample in Hangzhou West Lake district. The conclusion can be drawn that the richness and diversity index of plant communities in street greenbelts are not very high, which showing that the community type and structure are single, and species in the plant communities are not very abundant。(6) The result of the 15 comprehensive appraisals of the plant communities on Hangzhou street greenbelt showed the GradeⅠtakes 27 percent, GradeⅡtakes 53 percent GradeⅢtakes 20 percent. It also showed that there is much need to be improved.(7) Based on the analysis, optimize the urban streets of plant community structure is following:Increase in native species of green space in the streets; increase community richness, build relatively healthy, stable communities; follow the laws of nature, considering the dynamic community succession law; to promote eco-conservation technology (8) Based on the analysis, optimize construction of urban street landscape is following: combined with site conditions, building characteristics, landscape; build complex layer structure of plant communities, rich in plant diversity; rich plant communities and seasonal changes of color changes; respect for nature, and create a community close to the natural landscape; focus on landscape function in harmony with the ecological effects; respect the laws of nature, to improve the level of maintenance and management of green space...