| This research taked the Yangtze River Delta as the research scope.Through th-e four latitude with 13 cities in total of 520 urban forest plots were investigated.A-nalysis of the Yangtze River Delta urban forest flora,urban forest communities of the whole characteristics,community characteristics of geographic zoning,and classifi-cation system of urban forest landscape was proposed.The study is in order to provid-e a theoretical basis for the construction and development of the Yangtze River De-lta green cities and urban forests.The main research results are as follows:1.According to Wu Zhengyi's classification method of Chinese seed plants distribution,the Yangtze River Delta urban forest floristic composition were analyzed in detail and found the followingcharacteristics:plant species are rich in the Yangtze River Delta,geographical element is relatively complex and temperate plant species are main vegetation type,followed by tropical plants.2.It was recorded 244 species of trees belonging to 63 families and 154 genera.Among them,there are 51 families and 109 genera and 109 species in urban background and 55 families,105 genera and 144 species in urban man-made forests.From the species composition,the Yangtze River Delta Urban Forests mainly composed of Rosaceae,Fagaceae,Leguminosae,Lauraceae,Moraceae,Ilex,Magnolia,Oleaceae,Camellia,Euphorbiaceae,Aceraceae,Taxodiaceae,composed of 64.7%of the total number of species,58.4%of the total number of genera.It accounts for 64.7%of the total species and 58.4%of the total genera.On vegetation type,which involved a total of subtropical evergreen broadleaf forest,evergreen and deciduous-broadleaved mixed forest and temperate deciduous broad-leaved forest green summer three vegetation zones.Urban background forests and urban man-made forests,their main families and genera are similar,but there are differences in the quantity distribution and order.3.The general characteristics of forest plant community showed that species di-stribution is relatively concentrated in urban forests of Yangtze River Delta.The to-p 30 tree species in the urban background forests and urban man-made forests acc-ounts for 70.1%and 76.66%of important values respectively.The two curves are "L"shaped,but the tree species distribution are more uniform in urban background forest-s than in urban man-made forests.Ranked 1-3 trees species in urban man-made fo-rests have large proportion of important values.They correspond to species:Cinna-momum camphora,Platanus acerifolia,Osmanthus fragrans.These three species occ-upy a very important position in urban man-made forests of the Yangtze River Del-ta,especially Cinnamomum camphora as the most,accounting for 31.62%of the t-otal urban man-made forest important values.4.Species of Margalef index Pielou index,Shannon Wiener index and Simpson index of statistical analysis results in urban background forests were all showed as follows:34°N<32°N<30°N<28°N.It shows that communities of species richness,evenness and species diversity changes in urban background forests were decreasing from south to north,which was consistent with the trend of environmental factors like heat,temperature and humidity,in the Yangtze River Delta region.5.Community Characteristics of different latitudes in the Yangtze River Delta were as follows:(1)The number of species The number of forest trees on the four latitude basically presents an parabolic distribution,that is,less in Head and tail(28°N and 34°N),and more in middle(30°N and 32°N).From west to east,that is,from inland to the coast,there was an increasing trend in the number of trees.This trend was more significant in 34 ° N and 32 °N than in 30 ° N and 28 ° N,the north was more significant than in the south.(2)The proportion of evergreen trees and deciduous trees From north to south,that is,with decreasing latitude,the proportion of evergreen trees and deciduous trees showed an increasing trend.Local area due to small environmental impact,was made change slightly in proportion.From west to east,the proportion of deciduous trees and evergreen species also showed an increasing tendency that the nearer the coast,the greater the proportion of the number of evergreen species.Among them,the cities whose proportion of evergreen trees and deciduous trees reached 1:3 were:Lianyun District of Lianyungang,zhuji County of Shaoxing,zhoushan island,Qingyuan County of Lishui.(3)The proportion of conifer and broadleaf trees the proportion of coniferous and broad leaved tree species has gradually increased from west to east.However,during which there were affected by the terrain,such as Chunan and Fuyang District of Hangzhou,were mainly affected by topography.(4)Important values of tree species The urban man-made forests in 34°N Latitude and 32°N Latitude were mainly composed of Platanus acerifolia,Populus × canadensis and Cinnamomum camphora.There were similar proportions of the three tree species.Tree species are mainly composed of Cinnamomum camphora.Urban background forests in Various latitudes had significant differences from urban man-made forests in the composition of tree species.There were big difference around the urban background forests and It was well integrated with the local climate,topography and other site conditions.The differences of urban man-made forests were relatively small around Yangtze River Delta region,and homogeneity tended to be more apparent.(5)Number of related species From the overall trend,28°N>30°N>32°N>34°N,from north to south,the number of species association increased significantly with the decrease of latitude.The more the related species,the higher the species richness and the greater the stability of the communities.6.From the perspective of landscape,it was after Investigation and analysis,urban forest communities in Yangtze River Delta were classified systematically from the angle of tree form.From the perspective of landscape aesthetics,try to solve the problems such as landscape elements mix and distribution of community tree species.This was a new attempt. |
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