| This study made research on urban forest wood plants in Tangshan city, investigated species composition of trees, the important value, height, DBH, health status, leaf area index and so on for the analysis of structural characteristics, viewing of 50 communities chosen from four urban forest types of street trees, residential communities, functions parks and campus of University. And then, comparative analysis of species richness, diversity, evenness, for four types of urban forest. study the characteristics of species diversity and the structure of woody plants in urban forest of Tangshan. Urban forest structure is the three dimensional spatial arrangement of vegetation in urban areas, which it provides the basis information to comprehend integratively the urban forest ecological functions and to be utilized for city ecological layout. Tree species diversity of urban forest (tree species richness, diversity, evenness etc.),on the other hand, is the important index for reflecting the stability and health condition of urban forest community in terms of complexity and organization of urban forest community structure and function. In order to provide basis information to instruct urban forest construction, the structure characteristics and species diversity of urban forest in urban area were investigated by sampling plots in Tangshan. The main results are showed as follows:1 In this study scope, there are 110 kinds of trees, located in Section 37. These types of individuals accounted for a significant number of the status of only a few species. the number of the first 15 species accounted for 62.35% of total investigations, as the species composition monotonous landscape plants make the rich enough, and It is easy to increase the Instability of urban forest.2 The rank of important value of urban forest in Tangshan tree species were Populus> Robinia seudoacacia > Sopora japonica> Platanus orientalis> Buxus sinica> Lonicera maackii> Ligustrum quihoui> Salix babylonica> Platycladus orientalis> Prunus triloa> Prunus persicaf> Sabina chinensis> Ginkgo biloba> Berberis Vulgaris> Pinus tabulaeformis, the first 11 species are common species, nearly all of the 73% of species in Tangshan City, Other species of urban ecology, environmental protection and beautification of the role played by the relatively small. Reflecting the city of Tangshan Green relatively single species.3 The constitutes of urban forest in Tangshan were those of young stand, of which those DBH less than 10 cm take up 42.6%. Less- managed forest lands (e.g., residential area forest land) had the highest proportion of small trees, whereas intensive-managed lands(e.g., street trees, campus forest land),particularly those managed for a relatively long period, tend to have a higher proportion of large trees.4 There is a tendency in diversity index among different layers of urban forest community, in which the complicated composition community has a higher trees amount in different stand layers in compare with the simple one. Among the different layers of urban forest community. The indexes of campus forest type are higher than the other urban forest types.5 Used the ratio of arbor and shrub, ratio of conifer and broadleaf , ratio of local tree species and exotic tree species to analysis the distribution of species of urban forest in Tangshan. Park forest planting ratio of arbor and shrub is 1:5.2, close to the reasonable planting ratio of arbor and shrub 1:6. Campus forest planting ratio of conifer and broadleaf is 1:2.8, close to the reasonable planting ratio of conifer and broadleaf 3:7. Park forest planting ratio of local tree species and exotic tree species is 5:3, close to the reasonable planting ratio of local tree species and exotic tree species 6:4.6 The total health of urban forest investigated in Tangshan was classified as being in medium condition. The sequence of health condition from higher to lower in different urban forest types is Park forest>Campus forest > Residential area forest>Street trees. The factors related to health of forest, besides protection, are thesis of surroundings stresses(e.g., salt, soil compaction, vandalism, injury),Plant competition(related to tree density) and natural aging processes (tree size).7 Urban forest trees of different types of leaf area and leaf area index showed that the proportion of leaf area of Park forest trees is the highest for 43.6%, accounting for only 8.7% in residential areas; Park forest leaf area index is the highest for the 5.81, the minimum for residential areas is 2.73.8 From the urban forest structure, species diversity and health status of trees, conducted a reasonable assessment of the forests status of Tangshan City, from the distribution and layout of urban forest, tree species selection, distribution, etc., for the urban forest construction in Tangshan City putting forward reasonable proposals.
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