Study On Landscape Evaluation And Improving Countermeasures Of Highway Green Space System In Nantong

Greening is now regarded as an essential work of highway construction,and an important part of land greening in China.In past years,the development of highway has created convenient transportation,but also brought substantially negative impacts on environment in China.Highway greening has been regarded as one of treatments to alleviating the pressure on the environment during the highway construction.With the development of highway construction,the concept of highway greening were continually deepening,and the design concept were constantly updated while methods were renovated.The study chooses arterial highways in Nantong as research object,then carried out research on the improvement and optimization of highways’ landscape quality.It analyses and evaluates the vegetation ecology by species composition and community structure.It applies vegetation ecology methods,for example,community species composition,community quantitative features,community life-form spectrum,community species diversity and community similarity coefficient,and the theory of landscape ecology to study communities.After that,by quoting the concept of three-dimensional green volume,the study calculates the quantity of carbon fixation,oxygen release,cooling and humidification.Furthermore,it makes a comprehensive evaluation of arterial highways’landscape quality,and then establishing an ecological landscape quality evaluation system of highway-greenbelt by the way of PCA(Principle Component Analyses).The results are as follows:(1)There are abundant plant species of highway-greenbelt in Nantong.Road G228 has the largest number of 59 species of plant,Road S335 has the minimum number of 30 species.It shows similarity among the species which have the highest IV(importance value)in tree layer and shrub layer of 5 arterial highways,which is also the same to the tendency of life-form.The result shows the feature of high human intervention.Species diversity of tree layer is higher than shrub layer in the 5 arterial highways.It has a high species similarity among the plant communities and landscape styles of all highway-greenbelts.(2)The study calculates the green volume of phytocoenosiums in 5 arterial highways,Road G204 has the largest green volume per unit area(4.48 x 104 m2/hm2),followed by Road G15(3.16 × 104 m2/hm2),G228(1.91 × 104 m2/hm2)and S334(1.84 × 104 m2/hm2).The most effective factor in ecological benefit of the greenbelt is green volume of plant community.The oxygen release per unit area shows positive correlation with the solid carbon per unit area(Road G204>Road G15>Road G228>Road S334>Road S335).Road G204 has the highest carbon quantity per unit area of 36.80g·m-2·d-1,and the oxygen release per unit area is 30.10 g·m-2·d-1.The lowest one is Road S335,which carbon quantity per unit area is 14.92 g·m-2·d-1 and oxygen release per unit area is 12.16 g·m-2·d-1.From higher amount of cooling unit area to lower is Road G204,Road G15,Road S334,Road G228 and Road S335.And Road G204’s cooling effect per unit area is 1.14℃ m-2 ·d-1,Road S3 3 5 is 0.480℃ · m-2 · d-1.The sequence of humidification quantity per unit area is Road G204>Road G15>Road S334>Road S335>Road G228.Road G204 also has the largest number of 6994.51g·m-2·d-1,and Road G228 has the smallest number of 3121.19 g·m-2·d-1.(3)Next,this study makes comprehensive evaluation on landscape ecological quality of 5 arterial highways by the way of PCA.The sequence of composite score is Road G204>Road G15>Road S334>Road G228>Road S335,while Road G204 has the score of 2.329,and Road S335 has the score of 0.146.Finally,the study tries to establish construction standards and configuration mode of highway-greenbelt in Nantong based on the above results,and puts forward an optimized scheme of highway-belt’s afforestation mode.In addition,it studies planting technologies for highway greening in Nantong.This research will provide theoretical foundation to promote the level of highway landscaping construction and highway service in Nantong.Meanwhile,it will provide scientific basis to promote landscape quality and economic effects of highway greening.