Study On Flora And Plant Community Characteristics Of Steep Slope In Central Districts Of Chongqing

Plant community of steep slope,as a special type in city plant community,is an indispensable part in urban green space.Virescence of steep slope can not only increase the type of city green space,beautify the city,increase the coverage of green space,but also increase the eco-efficiency. By studying the plants growing on the steep slope in central districts of Chongqing,this paper analyzed the characteristics of plant flora,the species composition and biological structure of steep slop in different habitat.The dominant native plant species were summarized.By combining the theory of phytology,urban ecology and restoration ecology,the community types and native plant species for vegetation restoration were proposed,which supplied scientific foundation to the construction of steep slope plant community.The main research results are as follows:1.The characteristics of steep slope flora were as follows:There are 381 species of steep slope plant in total,belonging to 118 families and 285 generics in the area.Dicotyledones plants are predominant in the flora.The numberof the family and generic which contains numerous species is less,while the family and generic which contains single species is the most in quantity;Herbage is the most,and perennial herbage is the predominant part in the herbage,shrub is less than the herbage,arbor and liane are comparatively fewer.The plant which loves the environment of enough sunlight,warm,acid and can tolerate drought is comparatively much.There are manily native species.The cosmopolitan family and generic takes a certain propotion.Transitional characters of geography were obvious because the temperate elements and the tropic elements infiltrate each other.It is low in endemic element.2.By cluster analysis,seven vertical stratification types(liane,herbage,shrub,shrub-liane, arbor-liane,arbor-shrub-liane or arbor-shrub-herbage and arbor)were devided,and the type of liane, shrub and shrub-liane is more than others.After research the community structure of each type in different habitat,it concluded:(1)the liane type was much on the artificial environment,cement or rock,slope >85°steep slope;(2)the herbage type was much on the 76-85°and 6-10m steep slope; (3)the shrub type was much on nature or artificial environment,purple sandstone(shale)and 6-10m steep slope.(4)the shrub-liane type was much on artificial environment,cement or rock and 76-85°steep slope;(5)the arbor-liane type was much on artificial environment,cement or rock and 76-85°steep slope;(6)the arbor-shrub-liane or arbor-shrub-herbage type was much on nature environment,purple sandstone(shale),76-85°and height >10m steep slope;(7)the arbor type was much on "other"matrix,slope>85°and height<10m steep slope.3.As to the plant composition:Broussonetia papyrifera and Ficus virens var.sublanceoIata were the predominant species in the arbor layer,while Neosinocalarnus affinis,Erythrina variegate and Melia azedarach were a little less;Broussonetia papyrifera was the predominant species in the shrub layer,while Distylium racernosum,Ligustrurn sinense,Ficus virens var.sublanceolata and Viburnum odoratissimum var.awabui were a little less;Parthenocissus tricuspidata,Humulus scandens,Jasminum rnesnyi,Anredera cordifoliam and Pueraria lobata were the predominant species in the liane layer;Sinosenecio olahamianus was the predominant species in the herbage layer,the wild plant,such as Pteris vittata,Miscanthus sinensis,Sambucus chinensis,Arternisia argyi,etc.were a little less.The richness of arbor was higher than shrub,its diversity was lower than shrub and its evenness was lillle higher than shrub.The richness,evenness and diversity of liane were lower than herbage.After research the composition of each type in different habitat,it concluded:(1)arbor's richness was high on nature environment,6-10m and 401-1000m² steep slope,while its evenness was high in the environment of yellow sandstone and limestone,and its diversity was high on yellow sandstone,sunny slope and half-shady slope,6-10m and 100-1000m² steep slope.(2)the shrub's richness was high on nature environment,purple sandstone(shale),slope >75°,shady slope, height >5m and area >100m² steep slope,while its evenness was high on half-natural and 6-10m steep slope,and its diversity was lower on artificial environment,60-75°and area <100m² steep slope than other habitat.(3)liane's richness was high on nature environment,half-shady slope, 6-10m and 100-400m₂ steep slope,while its evenness was high on half-natural environment,purple sandstone,yellow sandstone,limestone,60-75°,slope>85°and half-shady steep slope,and its diversity was the lowest on the artificial steep slope,limestone and cement or rock,while it was the highest on the yellow sandstone;(4)herbage's richness was high,and its evenness was high on nature environment,artificial environment and sunny slope and its diversity was high on nature environment,artificial environment,yellow sandstone,sunny slope,half-shady slope and 2-5m steep slope.4.It concluded from the cluster analysis that,the most community on steep slope in Chongqing was Broussonetia papyrifera + Ficus virens var.sublanceolata - Anredera cordifolia + Humulus scandens + Jasminum mesnyi - Sinosenecio olahamianus community,Parthenocissus tricuspidata,Ficus virens var.sublanceolata,Broussonetia papyrifera,Humulus scandens, Viburnum odoratissimum var.awabui - Jasminum mesnyi,Viburnum odoratissimum var.awabuki + Malvaviscus arboreus var.penduliflorus and Mucuna sempervirens + Humulus scandens community were a little less.And there were also some special predominant single-species community,such as Jasminum mesnyi,Bougainvillea glabra,Rosa shybrida,Sinosenecio olahamianus and Trachelospermum jasminoides community etc.According to the cause, Broussonetia papyrifera + Ficus virens var.sublanceolata - Humulus scandens - Sinosenecio oIahamianus community was the predominant community on the natural steep slope.Broussonetia papyrifera + Ficus virens var.sublanceolata - Humulus scandens + Parthenocissus tricuspidataSinosenecio olahamianus,Broussonetia papyrifera - Humulus scandens + Jasminum mesnyiRoegneria kamoji + Daucus carota community were the predominant community on the half-natural steep slope.While on the artificial steep slope,Broussonetia papyrifera - Jasminum mesnyi community was the predominant community,Parthenocissus tricuspidata + Jasminum mesnyi and Ficus virens var.sublanceolata community were a little less.5.There are 124 species of native plant that can be applied to landscape virescence.According to the characteristic of steep slope environment and the target of the community construction,it proposed in the future steep slope plant community configuration that:(1)when matrix,direction and location of the steep slope are considered,the biological and ecological habit of plant is the most important basis in the plant configuration;(2)when slope,height and area of steep slope are considered,for the stability of the slope,the dealing way of the slope is the most important basis;(3) there are seven types of community(herbage or herbage-flower community,vine community,shrub community,arbor community,shrub-herbage or shrub-liane community,arbor-liane community, arbor-shrub-herbage or arbor-shrub-liane community)that are commonly applied to the construction of steep slope.