| This paper selects 24 roads(a total of 120 road sample sections)in the reconstruction project of the first ring,ten horizontal and ten vertical roads in Zhengzhou as the research object,and investigates and studies the characteristics of plant community structure and diversity,the average height of street trees,canopy line,planting density and planting spacing,width height ratio(D/H),canopy density and landscape configuration mode,Based on the data obtained by lidar technology and using statistical methods to analyze the problems existing in the spatial structure of street trees,select typical road sample sections to analyze and summarize the causes of the investigation and research results,so as to provide some references for the improvement and reconstruction of road green space in Zhengzhou.The main results are as follows:1.Through field investigation,it is found that there are 38 species of trees,34 species of shrubs and 32 species of herbs in the road green space in Zhengzhou,belonging to 105 species,81 genera and 52 families.Among them,there are 38 evergreen species and 34 deciduous species.The families containing more plant species are: Rosaceae(9 genera and 12 species),Oleaceae(3 genera and 6 species),Liliaceae(3 genera and 4 species),Labiatae(3 genera and 4 species),honeysuckle(3 genera and4 species),Pinaceae(2 genera and 3 species),Aceraceae(1 genus and 3 species).The tree species richness in the road green space is 6.75,the diversity index(Shannon index)is 1.56,and the evenness index(Simpson index)is 0.59,which reflects that the tree layer(street tree)of the first ring,ten horizontal and ten vertical roads in Zhengzhou is rich in plant species and has high diversity,but the evenness of the tree layer is not enough.2.The plant community of road green space is divided into evergreen deciduous mixed type and deciduous broad-leaved type.The evergreen deciduous mixed type is the main model,followed by deciduous broad-leaved type.In the survey of 120 road sample sections,there are 12 roads with evergreen and deciduous mixed type as the main landscape,12 roads with main street tree species of Ligustrum lucidum,Photinia,cedar and deciduous broad-leaved type as the main landscape,and 12 roads with main street tree species of Fatong,gingko,maple poplar,ash,purple leaf plum,etc.3.The average height of roadside trees in road green space is 11.77 m,14 roads above the average height and 10 roads below the average height;Among them,the highest average height of street trees is Wenhua Road,which is 14.85m;The lowest is the East Third Ring Road,with an average height of 9.18 m.The planting density of street trees ranges from 60 trees/hm~2 to 164 trees/hm~2;Among them,the planting density of trees in the future road is the largest,164 trees/hm~2;Dongfeng Road takes the second place,162 plants/hm~2;Jinshui road and Jiangshan road rank third,with140 plants/hm~2.The average tree planting density of 24 roads is 108 trees/hm~2,and12 roads are higher than the average tree planting density,accounting for 50% of the total roads.The planting spacing of roadside trees is within 5m-10m,and the road sample sections with planting spacing of 5m,6m and 7m account for a large proportion.The average width to height ratio of 24 roads is 21.5.Among them,the largest width height ratio is Zhongzhou Avenue,which is 9.86,and the smallest is jingsan Road,which is 3.23.The aspect ratio is positively correlated with road grade and road width.The higher the grade and width of the road,the greater the ratio of width to height,and the sense of road space enclosure is reduced,resulting in the feeling of emptiness and dispersion.The average canopy density of roadside trees on 24 roads is 0.28,and the highest canopy density is jingsan Road,which is 0.63;The lowest is Jingguang Road,which is 0.04.The canopy density of trunk road is greater than that of expressway.The canopy density decreases with the increase of road grade,and the road grade is negatively correlated with the canopy density.4.The overall shape and tortuosity of the contour are selected for quantitative analysis of the canopy line.The results show that the overall shape of each plate canopy line is concave convex composite type,and the tortuosity of the canopy line increases with the increase of the road plate.The shape of the canopy line is preferably concave convex composite type,and the maximum number is 2-3.The tortuosity of the canopy line(△H/△ L ratio)range is [0.1,1].5.The landscape configuration mode of roadside tree green belt is relatively simple,mostly single-layer tree structure,and the types of trees are relatively not rich;The green space of the central car separation zone includes six landscape configuration modes: arbor + shrub + hedge,shrub + hedge,arbor + hedge,hedge,arbor + shrub and shrub,and the overall landscape characteristics are mostly regular,supplemented by natural;The split green belt on both sides includes three landscape configuration modes:arbor + hedge,arbor + shrub + hedge and shrub + hedge.The configuration modes in the same road are also different,and the landscape configuration modes are flexible and diverse. |
