The Study Of Structure Characteristics And Ecological Function Of Urban Forest In Zunyi City

As an important part of urban forest, street trees play an important role in improving urban environment. The author analyzed the distribution pattern and characteristics of the main street trees in the urban region of ZunYi and studied their main ecological functions. Meanwhile, based on the analysis of species structure of the main typical forest community in FengHuangshan forest park, the comprehensive benefits of the urban forest in ZunYi city zone were preliminarily assessed, and the ways to optimize the structure were proposed. The main results were as follows: (1)There are more than 20 street tree species in ZunYi urban region. Several species took a large part. Native species were relatively few. (2)The average BHD level was low, of which those less than 10cm take up 47%. The total biomass of street trees was equal to that of 19hm2 forest,6-8 hm2 forest should be planted in the central region. (3)The total biodiversity index was 0.924, which implied that the species structure of urban main roads were relatively simple. (4)The total leaf area (LA) of street trees was 1.345×106m2 and the average leaf area was 61.5m2 per tree. The average LAI was 0.65. The difference of the average leaf areas between species along varied roads was significantly remarkable. (5)The dust removals per leaf area of species such as Platanus acerifolia,Ligustrum Lucidum ,Maqnolia grandiflora and Prunns cerasifera were superior to that of species such as Salix matsudana,Populus Canadensis,Ulmus pumila,Cinnamomum camphora etc. The dust removal per leaf area of Platanus acerifolia was especially high. (6)The leaves of Ligustrum Lucidum,Prunns cerasifera,Salix matsudana,Platanus acerifolia,Elaeocarpus decipiens,Maqnolia grandiflora,Livistona chinensis,Populus Canadensis had better absorption to heavy metals than those of Erythrina corallodenron,Ginkgo biloba,Cinnamomum contractum,Citrus sinensis,Trachycarpus fortunei,Myrica rubra. The content of heavy metals in tree leaves along Waihuan road, Fenghuangzhong road, Gaojiu road, Haifeng road were much more than those of trees along other main streets. (7)The leaves of Ligustrum Lucidum,Ligustrum quihoui,Populus Canadensis,Cinnamomum contractum,Maqnolia grandiflora,Citrus sinensis,Erythrina corallodenron had better absorption to SO2 than Prunns cerasifera,Platanus acerifolia,Cinnamomum camphora,Livistona chinensis and Ulmus pumila. (8)The species structure characteristics in the forestry park were limited composition, mass distribution, inferior BHD classes etc. In general, the forest park had forest functions. (9)The species diversity of the forest park was relatively low. Native species and appropriate alien species should be chosen to add. (10)The stand of the forestry park could be classified to coniferous and deciduous mixed forests, deciduous broad-leaved forests and evergreen deciduous broad-leaved mixed forests according to clustering analysis. Their Simpson index and Shannon-Wiener index decreased in the same order, which stated the forest community succession in FengHuangshan Forest park. (11)In the ordination of both the important value and the total dominance of different species in FengHuangshan Hill forest park, Adhatoda vasica took the first place. But the roles of a species played in a community couldn't only be decided by the two indicators.