Vegetation Characteristics And Noise Reduction Of Road Landscape Forest Belt Along The Yellow City Belt In Ningxia

China’s urbanization has entered a new stage,the urban transportation system has become more and more developed,and urban noise pollution has also followed.As an important part of urban infrastructure construction,urban greening is an important means to create a green space system for ecological city construction and the core content of urban ecological environment construction.As a measure to improve the traffic environment,road landscape forest belt can not only improve air quality,reduce urban noise,relieve driving fatigue,but also coordinate and beautify the road landscape.In this study,through field investigation,monitoring and quantitative analysis methods,were selected four major cities along the Yellow City Belt in Ningxia,such as Yinchuan,Wuzhong,Zhongwei,and Shizuishan,and 52 sample plots with different community characteristics in a total of 25 backbone roads were carried out.The survey of vegetation community characteristics mainly includes tree species composition,canopy density,canopy width,and vegetation configuration pattern.Real-time road traffic noise monitoring was carried out along the horizontal and vertical directions of the road during the full-leaf period and the dead-leaf period of the plant,to explore the forest belt characteristic factors that affect the traffic noise attenuation effect of the forest belt community,and to analyze the noise reduction ability of forest belts with different structural characteristics.The main results are as follows:(1)There were a total of 66 species of common greening plants,covering 26 families and 45 genera.The ratio of trees,shrubs,and grasses is 2.36:1.36:1.There were fewer evergreen tree species and fewer shrub vegetation species.The three-board and four-belt type was the main road type.The overall vertical level of the forest belt was relatively rich,and the configuration mode of trees,shrubs and grasses was dominant.(2)Seasonal changes lead to changes in the external morphology of plants,and the noise reduction effect of forest belts in the full-leaf stage was better than that in the dead-leaf stage.The correlation analysis of the cumulative attenuation of traffic noise and various characteristic factors in 41 sample plots found that there was a significant correlation between the attenuation and road types,while the correlation between traffic flow and attenuation was not significant.Under-branch height showed a significant negative correlation,and a very significant positive correlation with forest belt canopy closure.(3)The distance between 0 and 10 m in the landscape forest belt was the effective noise reduction distance.The noise reduction effect was the best within this distance.With the increase of the distance,the noise reduction effect showed a decreasing trend,and the noise reduction effected weakens with the increase of height.When the height of the sound source was close to the monitoring height,the noise reduction effect was the best.(4)The more complex and diverse the vertical structure of the plant community,the richer the configuration patterns,and the more significant the noise reduction effected.The noise reduction effect of each arrangement of forest belts was from high to low:stepped type>staggered type>determinant type>mosaic type.(5)In order to enhance the noise reduction effect of the forest belt,different planting methods can be adopted.This study believed that the plant configuration mode with better noise reduction effect is tamarisk+pavement cypress+juniper+dry willow+silk cotton wood and arborvitae+purple leaves The combination of evergreen and deciduous tree species with low branch points,such as plum+juniper+silk cotton wood+ailanthus,was regularly arranged in a mixed dense planting method.