Studies On The Structure Of The Urban Green Space In Hohhot

The study is focused on the urban green space structure. By using the recent study results of the structure of urban green space both at home and abroad for reference, and also taking the present situation in China of this research area into consideration, an investigation and analysis has been made on the layout of the green space and the structure of the plant community of this city. In order to evaluate the structure of urban green space of the city, the evaluation index system with the total 33 indices has been established from the following three aspects:the layout of the urban green space, the ornamental trees and the compositions of the botanical communities. By using the methods and the system, synthetical evaluation has been operated.on the urban green space structure (including: green space layout structure, the ornamental tree species, the landscape aesthetic and structure of plant community) and the methods specially for constructing them has coincided with its features and functional requirements. It is shown that:(1) The indices of the urban green space of Hohhot are on the low side. The average ratio of the attached green space is about 15% and.the average ratio of the street green area in the central city areas is also not enough; The coverage of roadside green space is at the average level; the green area for environmental protection is seriously low; the green space system for disaster prevention hasn't been established yet; the distribution of public green space is not even. The results of the comprehensive evaluation of the layout structure of urban green space of Hohhot can be grades as III, which means at medium level.(2) There are altogether 78 woody tree species in the research area. As a whole, the proportion of the arbor to the shrub is about 1:0.8, evergreen trees and deciduous trees are 1:1; There are 34 indigenous tree species altogether, which take up 28% among the total indigenous tree species with the value of 62% of naturalness; the significant values of the arbors and shrubs according to the sequences from high to low are as follows:the order of the first 10 arbor tree species is Pinus tabulaeformis (25.7%)>Picea meyeri (21.8%) >Sophora japonica (12.1%)>Prunus davidiana (11.5%)>Ulmus pumila (11.4%) >Robinia pseudoacacia (10.4%)>Euonymus bungeaun,Populus canadian (10.2%) >Salix matsudana (9.9%)>Platycldus orientalis (9.7%); the order of the first 10 shurb tree species is Syringa oblata (65.6%)>Prunus triloba (35.2%)>Sorbaria kirilowii (33.9%)>Cotoneaster multiflora (26.8%)>Rosa rugosa (20.5%)>Securinega suffruticosa (14.7%)>Forsythia suspensa (14.5%)>Ligustrum quihoui (11.1%)> Cornus alba(10.3%)>Rosa xanthina(8.8%). The average height of the arbor tree species is 6.5m with the average diameter of breast-height as14cm and the average height of shrubs is 2.0m.(3) The average number of tree species in the quadrate of plant community ranges from 6 to 8. The average mingling value is 0.58; The average ratio of different forest layers is 0.44; the average density of the arbor trees is 4.3 trees per 100m2, and for the shrubs is 3.4 trees per 100m2; the average coverage is 0.45; the average leaf area index is 3.2m2/m2; the average Gleason richness index is1.14, Margalet richness index is 1.8, Shannon-Wiener landscape diversity index (Shannon-Wiener diversity) is 1.55, Simpson diversity index is 0.72, the evenness is 0.82.(4) Landscape aesthetic values of plant community are as follows:the average value of plant community in residential area is 0.77; plant community of street gardens is 0.72,plant community of parks is 0.60, plant community of the unit green area is 0.74 on average, the average aesthetical value of plant landscape in is 0.71 on an average.(5) Comprehensive evaluation value of the plant community are as follows:plant community of residential district is 0.61,0.60 for the plant community of the average gardens; 0.57 for the plant community of the work unit; plant community in parks is 0.53, in conclusion, the value of the structure of the plant community in Hohhot is 0.58, which is at medium level.