| Roads have an important impact on the composition,structure and reproduction of urban flora and fauna.Plants along the road often exhibit characteristics that are significantly different from those of the surrounding plants.Spontaneous plants are an important part of urban biodiversity.This study takes the road green space in the main urban area of Nanjing as the research object,and investigates the composition of spontaneous plants in the road green space in spring,summer,autumn and winter,and analyzes the species composition characteristics of the spontaneous plants in different types of roads.Research indicates:(1)Among the 805 survey sites,327 species of 239 genera were found in 80 families of spontaneous plants.Among them,there are 21 species of 18 genera and 15 species of trees,15 species of 14 genera and 11 species of shrubs,13 species of 12 genera and 8 species of woody vines 123 species of 97 genera and 37 species of one-or-two-year-old plants,and 155 species of 122 genera and 50 families of perennial plants.Compositae,Gramineae,and legumes are the most abundant species,with 37 genera and 52 species,23 genera and 25 species,and 14 genera and 17 species.(2)The floristic composition of the genus of spontaneous plants in the road green space reflects the climatic characteristics of Nanjing in the northern margin of the subtropical zone.There were 100 genera(41.84%)of temperate distribution type,the 95 genera(39.75%)of the tropical distribution type,and 41 genera(17.15%)of cosmopolitan distribution type.(3)There are certain differences in the diversity of spontaneous plants in different grades of roads.Among them:87 fast-track green space plots,recorded 134 species of 108 genera in 47 families of spontaneous plants,with an average number of species of 7.66±5.52 per plot.There are 8 kinds of high frequency species with frequency more than 20%,namely,Conyza canadensis,Alternanthera philoxeroides,Setaria viridis,Oxalis pescaprae,Sonchus oleraceus,Polygonum aviculare,Youngia japonica,Oxalis corymbose.There are 49 plots in the main road green space,and 102 species of 87 genera in 38 families of spontaneous plants are recorded.The average number of species in each plot is 9,02±5.25.There are 13 species of high-frequency species,namely,Conyza canadensis,Alternanthera philoxeroides,Setaria viridis,Oxalis pescaprae,Sonchus oleraceus,Polygonum aviculare,Youngia japonica,Oxalis corymbose.,Solidago canadensis,Lepidium apetalum,Chenopodium album,Calystegia hederacea,Veronica persica,Plantago virginica,Sonchus arvensis.There are 413 plots of secondary trunk green space,recorded 249 species of 190 genera in 68 families of spontaneous plants,and the average number of species per plot is 6.88±4.78.There are 5 kinds of high-frequency species,namely,Conyza canadensis,Alternanthera philoxeroides,Setaria viridis,Sonchus oleraceus,Oxalis corymbose.There are 257 plots in the branch road green land,recorded 209 species of 158 genera in 58 families of spontaneous plants,and the average number of species per plot is 6.83±5.60.There are 7 kinds of high frequency species,namely,Conyza canadensis,Alternanthera philoxeroides,Setaria viridis,Polygonum aviculare,Galium aparine var.tenerum,Oxalis corymbosa,Chenopodium album.The similarity of spontaneous plant species in different road grades showed that the symbiotic plant species of the fast road and the trunk road sample had the highest similarity,which was 50.32%;the main plant and the secondary trunk symbiotic plant species had the lowest similarity,which was 35.00%.(4)The composition of spontaneous plants in the green space of different urban areas is quite different.There are 158 plots in the southeastern part of the city,and 205 species of 59 families spontaneous plants are recorded.The average number of spontaneous plants in each plot is 7.54±6.14,Among them,there are 5 kinds of high frequency species with frequency more than 30%,which are Oxalis corymbose,Alternanthera philoxeroides,Setaria viridis,Veronica persica,Galium aparine var.tenerum.There are 164 plots in the west of the city,and 96 species of 37 families spontaneous plants are recorded.The average number of spontaneous plants in each plot is 5.20±3.34.Among them,there are three kinds of high-frequency species,namely,Conyza canadensis,Sonchus oleraceus,Oxalis corymbose.There are 256 plots in the north of the city,and 153 species of 50 families in the spontaneous plants are recorded.The average number of spontaneous plants in each plot is 8.98±5.79.There are 6 kinds of high frequency species,namely,Conyza canadensis,Alternanthera philoxeroides,Sonchus oleraceus,Lepidium apetalum,Chenopodium album,Oxalis corymbose.There are 230 plots in the central city,and 165 species of 56 species in the spontaneous plants are recorded.The average number of spontaneous plants in each plot is 3.50±2.27.There is only one species of Oxalis corymbosa in the high frequency,with afrequency of 42.61%.The similarity of spontaneous plant species in different urban locations was found to be the highest in the west of the city and the north of the city,which was 41.48%.The similarity of the spontaneous plants in the west of the city and the central city was lowest with 31.82%.(5)The study recorded 54 species of 43 genera and 23 families belonging to invasive plants,accounting for 16.51%of the total number of spontaneous plants.Compositae has the largest number of invasive plants,including 12 genera and 15 species;followed by Amaranthaceae,including 3 genera and 6 species;Scrophulariaceae include 1 genera and 4 species.There are 6 kinds of high frequency species with frequency more than 10%in the road green space,belonging to 3 families and 4 genera,which are Conyza canadensis,Alternanthera philoxeroides,Sonchus oleraceus,Veronica persica,Sonchus asper,Veronica didyma.There are some differences in the distribution of invasive plants in different road grades.There are 70 fast-track plots of invasive plant distribution with 32 invasive plants,42 trunk road plots with 21 invasive plants,332 sub-continental plots with 46 invasive plants,180 branch plots with 3 8 species of invasive plants.Among them,the fast-track and the trunk road invasive plants have the highest similarity,which is 39.62%.The distribution characteristics of invasive plants in different urban locations are also different.Among them,there are 121 sites in the southeastern part of the invading plants with 35 invasive plants,155 sites in the west of the city with 23 invasive plants,228 sites in the north of the city with 32 species of invasive plants,120 sites in the central city with 29 species of invasive plants.Among them,the invasive plants in the west of the city and the north of the city have the highest similarity,and the similarity is 47.37%.(6)30 spontaneous plants with high ornamental value and no clear negative impact on the ecosystem were selected from 327 self-produced plants in the main urban road of Nanjing as the evaluation object,from the four aspects of flower viewing characteristics,fruit viewing characteristics,foliage characteristics and adaptability.The 13 objective indicators include flower,flower color,ornamental period,ornamental season,fruit color,fruit color,ornamental period,ornamental season,leaf size,leaf intensity degree,evergreen/deciduous,and adaptability were evaluated.According to the evaluation results,the sequence of garden development and utilization of these 30 species of volunteer plants was Sonchus arvensis,Physalis alkekengi,Pterocypsela indica,Chelidonium majus,Solanum nigrum,Cirsium japonicum,Youngia japonica,Fragaria vesca,Viola dissecta,Veronica undulata,Lindernia crustacea,Mazus japonicus,Vicia sativa,Ajuga ciliata,Taraxacum mongolicum,Lapsana apogonoides,Viola variegata,Leonurus artemisia,Ranunculus japonicus,Oxalis pescaprae、Viola philippica,Viola philippica,Bothriospermum chinense,Bothriospermum chinense,Kalimeris indica,Potentilla supina,Potentilla supina,Clinopodium chinense,Torilis scabra,Euphorbia helioscopia,Bothriospermum tenellum,Bothriospermum tenellum,Lysimachia candida,Gerbera anandria.According to the plant height,seasonal variation and habitat adaptability of the authigenic plants,suggestions for the construction of the self-produced plants in the spring,summer,autumn and winter seasons are proposed.For example,the spring adopts Euphorbia helioscopia,Lysimachia candida+Ajuga ciliate+Clinopodium chinense to form spring white purple flowering plant landscape,adopting Bothriospermum tenellum+Chelidonium majus+Pterocypsela indica to form a strong yellow-yellow landscape in summer,and adopting Viola dissecta+Taraxacum mongolicum+Youngia japonica to form autumn bright yellow landscape,adopting Lapsana apogonoides,Viola dissecta+Torilis scabra+Cirsium japonicum to form winter white purple flowering plant landscape.At the same time,according to the research results,it provides species recommendation and reference for the spontaneous plant landscape construction of urban gardens. |
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