Dynamic Change Of Structure In Urban Green Spaces-a Case Study In Nanjing City

The function is decided by the structure of urban green spaces. We investigated road, square,park and residential green spaces which built in period â… (before1988), period â…¡(from1988to1998), and period â…¢(from1998to2006) in Nanjing. Structure of the four types of urbangreen space was analyzed. The aim of this paper is to find out what the structure of urban greenspace changed in Nanjing. And the optimization of greenland structure was recommended. Themain research results are as follows:1. According to the study of road green-belt the number of species, regional plants andornamental species increased from period â… to period â…¢ while the proportion of trees decreaded.Species of road green-belt built in different periods were concentrated in few species. Thedominat specie of greenland built in period â… was Platanus acerifolia. While Cinnamomumcamphora was the dominat specie in period â…¡ and â…¢. According to the statistics the agestructures of dominat species were stable and decling in period â… . The dominat species in periodâ…¡were growing and decling. The dominat species were growing. in period â…¢. The horizontalstructure of road green-belt was much more complicated in period â…¢ and in which included thehighest proportion of multilayer structure green-belts. The plant configuration mode was the mostreasonable in period â…¢.2. The square green space which built in period â…¢ was the riches in species. The species,species abundance index, Simpson index, Shannon-Wiener index and the average comprehensivebio-diversity index were the highest in period â…¢ among three periods. Cinnamomum camphorawas the most important specie in square green spaces. According to the statistics the dominatspecies were growing in period â… . The dominat species in period â…¡and â…¢ were growing, stableand decling. The proportion of multilayer structure green-belts was the highes in period â…  whileit was the lowest in period â…¡among three periods. The proportion of regional species was thehighest in period â… .While it was below40%in period â…¡and â…¢. Generally residents aresatisfied with squares in Nanjing. They are more satisfied with squares built in period â…¢ thanwhich built in the other two periods.3. In park green space, broad-leaved forest was the most common plant community inperiod â… , evergreen mixed deciduous broad-leaved forest was common in period â…¡, conifer andbroad-leaved mixed forest and evergreen mixed deciduous broad-leaved forest were common inperiod â…¢. Species, species abundance index, Simpson index, Shannon-Wiener index, Pielouindex and canopy density were the highest in period â…  among three periods. There was a biggestnumber of multilayer structure green-belts in period â… . Species and the average comprehensivebio-diversity index were the lowest in period â…¢. There was a smallest number of multilayerstructure green-belts in period â…¢.4. In residential areas which built in period â…¢ the ornamental species was the richest while the proportion of regional plants was the lowest. The number of species, multilayer structuregreen-belts and bio-diversity had much to do with the construction time, location and economiccondition of residential areas.It is proposed that the regional plant resources should be taken good advantage to promotethe bio-diversity of urban green space in Nanjing and to form the landscape with Nanjingcharacteristics. The construction of urban green space and plant disposition should follow thelaws of nature in order to form approaching nature artificial plant community.