Study On The Landscape Evaluation And Adaptability Of Green Roof Plants In Nanchang City

Nowadays,as a kind of intensive greening and beautification mode,roof greening has become a reasonable way to improve the environment and promote new-type urbanization with the crisis of human-environment relationship and the pursuit of green ecology.This article made a systematic analysis on the status of roof greening in Nanchang city,including the species composition,ornamental charateristics,frequency,growth status,species diversity and structure of roof plants,then evaluated the intensive green roof and researched the adaptability of the extensive green roof plants,in order to summarize the suitable palnts and plant disposition mode in Nanchang.The aim is to provide reference for the plant landscape of green roof construction and promote the realization of “ Forest City,Garden City” of Nanchang.The main results were as follows:1.The survey covered 28 green roofs in the main urban areas of Nanchang.There were 119 species(refer to Annex 1)affiliated to 52 families and 86 generas,61 of them were native plants,and the dispersion was high.The ratio of trees,shurbs,herbs,vines and bamboos was 44:39:26:6:4,the ratio of evergreen trees and deciduous trees was 55:34.In the aspect of ornamental characteristic,foliage plants,flowering plants and modelling plants were at most,branching plants were less.In the aspect of frequency,Osmanthus fragrans,Acer lalmatum,Prunus lannesiana,Loropetalum chinensis,Rhododendron simsii,Phtinia×fraseri,Ligustrum japonicum Cynodon dactylon and Zoysia spp.were common species of roof greening in Nanchang.In the aspect of growth status,green plants grew better on the whole and healthy plants accounted for 81.5%.In the aspect of species diversity,there weren't any trees in the extensive green roofs,while the intensive green roofs had uniform population distribution with dispersive trees and abundant shurbs,and the Simpson index more than 0.6 and Shannon-Weiner index more than 1.0 of tree layer and shrub layer were about 52% and 68.2%,the Jsw index more than 0.7 were over 80%.In the aspect of plant arrangement mode,there were five configurations,the extensive green roofs had single plant space and intensive green roofs had abundant plant space.2.AHP and SBE were used for the evaluation of plant disposition of 22 intensive green roof in Nanchang.I established a comprehensive evaluation model of plant diposition landscape,which including 13 indexes in ecology,landscape and society.The results showed that the intensive green roofs' qualuty was better totally.And the results obtained by the two methods were similar.No.7,No.16,No.8,No.19,No.11,No.21,and No.13 roof greening plant landscape qualities were better than others,their commonness including: rich plant species,typical local characteristics,abundant growth types,ornamental characteristics and configuration structure,natural and lively,they could also meet the needs for the public.No.6,No.14 and No.22 roof greening plant landscape qualities were worse than others,although they grew plants,but the plant type was monotonous,community structure was simple,and lacked consideration of color collocation,seasonal change and social service function.3.I studied on the drought resistance,heat resistance and the observation for one year of 21 plants,found that Sedum lineare ‘JinYe',Sedum lineare,Sedum aizoon,Iris lactea,Sedum spectabile and Liriope platyphylla resisted drought best,Sedum spurium,Portulaca grandiflora,Sedum sarmentosum,Setcreasea purpurea,Iris tectorum and Sedum polytrichoides resisted drought better,Zephyranthes candida,Achillea millefolium,Phlox subulata,Dianthus gratianopolitanus,Rosmarinus officinalis,Oxalis triangularis and Thymus mongolicus resisted drought worse,Phalaris arundinacea resisted drought worst.According to the half lethal temperature,the heat tolerance of them was Sedum lineare(60.18?)>Liriope platyphylla(59.64?)>Zephyranthes candida(59.59?)>Portulaca grandiflora(58.95?)>Sedum lineare ‘JinYe'(58.17?)>Iris lactea(57.26?)>Sedum spectabile(56.73?)>Sedum sarmentosum(56.37?)>Sedum aizoon(56.01?)>Thymus mongolicus(55.99?)>Sedum polytrichoides(55.98?)>Setcreasea purpurea(55.97?)> 0riganum vulgare(55.92?)> Phlox subulata(54.92?)> Rosmarinus officinalis(54.33?)> Phalaris arundinacea(54.24?)> Sedum spurium(53.18?)> Dianthus gratianopolitanus(52.78?)> Achillea millefolium(52.71?)> Oxalis triangularis(52.29?)>Iris tectorum(51.64?).4.It was suggested that the suitable plant dispositions for intensive roof greening were as follows:(1)Prunus cerasifera-Malus halliana-Hibiscus syriacus-Osmanthus fragrans-Acer palmatum + Euonymus japonicus ‘Ovatus Aureus'-Loropetalum chinense var.Rubrum-Rhododendron simsii-Cycas revoluta + Rosa chinensis + lawn grass.(2)Camellia japonica-Prunus lannesiana-Lagerstroemia indica-Acer palmatum + Ilex cornuta-Rhododendron simsii-Photinia × fraseri-Ligustrum japonicum ‘Howardii'-Ilex crenata ‘Convexa' + Camellia sasangua + lawn grass.(3)Citrus reticulata + Photinia serrulata-Ponica granatum + Viburnum awabuki-Nandina domestica-Gardenia jasminoides-Buxus sinica var.Parvifolia-Pittosporum tobira + Setcreasea purpurea-Dianthus gratianopolitanus.It was suggested that the suitable plant dispositions for extensive roof greening were as follows:(1)Sedum lineare-Sedum lineare ‘JinYe'-Liriope platyphylla.(2)Sedum aizoon-Iris lactea-Sedum spectabile-Portulaca grandiflora-Sedum sarmentosum-Setcreasea purpurea-Sedum polytrichoides.