| Green road-side corridor is one significant kind of corridor with ecological and recreational values. In the course of fast urbanization, as a protective planning theory for nature protection,ecology protection and green space construction, green-covered way have been applied into landscape architecture, ecological conservation, urban planning and etc.Building green road-side corridor has been increasingly concerned in our country. And it is a challenging course on how to maximize the ecological functions of green road-side corridor to construct green spaces, plan eco-city and protect urban environment.In this study, investigation, analysis and comparison of the comprehensive background information on 37 typical plant communities which were chosen on three green road-side corridor in Chengdu that separately represent the green ring of the central area, the main entrance of the city and countyside and the outskirts fast-track were done to summarize the plant community status quo of green-covered way in Chengdu. Furthermore, the contemporary comparison of one-year long ecological functions monitoring of 18 most representative communities and open place with no plant cover which involves microclimate amelioration, carbon-fixed and oxygen-made ability, UVB screening effectiveness and noise attenuation summed up the characteristics of green road-side corridor ecological functions and concluded the ecological benefits of plant community in the mechanism of regulation and the relevance of ecological effects and community characteristics. At last, the study derived the critical factors of the plant community to improve the quality of the environment.Some results are given as follows:(1) Different plant community structures represent different improvement of microclimate. The plant community characteristics such as canopy density and leaf area index and the transpiration are main factors of microclimate change.(2) The carbon dioxide concentration in summer has linear correlation with leaf area index, canopy desity and tridimensional green biomass. Furthermore, combining the results of the previous studies, the carbon dioxide concentration not only correlated with leaf area index, canopy desity and tridimensional green biomass, but also had intimate connection with the structure and plant construction of the community.(3) Different plant communities show prominence differentiation of UVB screening effectiveness on the gradiation of canopy characteristics. It is significant positive correlation between UVB screening effectiveness and leave area index, canopy desity and canopy length. In brief, the plant community canopy characteristics determine the UVB screening effectiveness of the community.(4) Four factors of community structure that conclude canopy desity, average height, leave area index and tridimensional green biomass are main factors effect the function of noise attenuation. Those influence factors were divided into two sorts as canopy factor and leave area factor with accumulated contribution 78.47%. According to those results, some suggests are given as follows:The adjust and optimize of plant community depend on the function of the green road-side corridor. And the spatial distribution, design and species selection of the plant community should be based on vegetation, climate and the principles of landscape ecology. Adjust and optimize the overall arrangement, configuration and species construction to build the multi-species, multi-level, multi-functional green-covered way system with good landscape, environmental and ecological effects.(1) The main green-covered entrance of city and conutyside should focus on three points according to the problems of Guang Hua green road-side corridor. Firstly, increase the number of native trees which are fast-growing, with big green biomass and large canopy. Secondly, increase the width of the road on both sides of the belt to realize ecological area which is absolutely controled not less than 50m. At last, chose some species which have a strong adaptability, resistance, low maintenance and also with the performance of a big crown, large and generous leave, compact branches and leaves to increase the noise attenuation.(2) Improvely building the green ring around the central city should make full use of the 12 years developing experience of Living Water Park and thoroughly follow out the configuration by simulating nature forest idea. Furthermore, it is better to increase the proporation of native trees, the deciduous species and coniferous species to enrich the variety of different seasons.(3) In carring out the idea of simulating nature, the construction of green road-side corridor in countyside should adjust to local conditions and chose the native trees which are resistant, easy-breeding, with low maintenance and ornamental value as main kind. At the same time, optimize the vertical structure of the plant community can decrease the sparseness under the canopy. And appropriately add some small trees and shrubs not only decrease the sparseness under the canopy but also do some benefit for the diffusion of pollution such as car exhaust.
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