| With the stringent restrictions of urban construction and people’s demand for land,conditions are highly limited in terms of the construction of large-scale centralized green space.The trend of high density in urban development manifests itself not only in urban construction and population,but also in residential environment.Based on the reality above,the present study proposes the design of micro green space in high-density cities,taking Shenzhen,Hong Kong and Macao,three typical high-density cities,as the research objects,with an aim to resolve the actual dilemma of inadequate city greening,crowded space,poor quality of both indoor and outdoor life.In addition,the study also investigates the micro green space from macro to micro aspect and summarizes the environmental layout and present situation of three common types of micro green space in high-density cities,which are roadside green space,pedestrian-street green space and vertical green space.In view of the urgent construction and improvement of micro green space in high-density cities,site selection is carried out in Guangzhou in the present study and great importance has been attached to the site characters,perceived preference factors of users and site ecological effect of roadside green space,pedestrian street green space and vertical green space in Tianhe District of Guangzhou,including the measurements of air temperature,relative humidity,illuminance and air negative ions concentration,through the combination of structured observation and field survey,questionnaire,graphic description and actual site measurement.The present study further puts forward the design and improvement suggestions for micro green space in high-density cities and provides theoretical basis for easing the tension between the development of high-density cities and inadequate green space,increasing the urban green space and improving the ecological environment in cities of high density.The major research findings are as follows:1.Micro green spaces have been investigated and summarized in three typical cities of high density.(1)The most representative micro green spaces are investigated in Shenzhen,Hong Kong and Macao,respectively,for example,the pedestrian-street and vertical green space in Shenzhen,the roadside and pedestrian street green space in Hong Kong and the roadside green space in Macao.According to the characteristics of the function,plant composition and spatial pattern of green spaces,the current study summarizes the environmental features of micro green space.It is clear that five dimensions which can influence the perception of micro-green space are aesthetic dimension,physical dimension,ecological knowledge dimension,social dimension and individual dimension.Besides,the perception model of micro green space is proposed,which can quantify the influencing degree of perceived preference.(2)It is concluded that three kinds of green space-roadside green space,pedestrian-street green space and vertical green space,can serve as the representatives of micro green space in high-density cities,which will provide the basis for the study of green space types in high-density cities.2.The present study probes into the site types and spatial attributes of micro green space in Guanghou.(1)A preliminary investigation is undertaken in 62 micro green spaces of three types(roadside green space,pedestrian-street green space and vertical green space)in Tianhe District in Guangzhou.(2)It is determined that an in-depth study can be conducted in the roadside green space of the residential area near the central axis of Tianhe District,the green space in commercial and residential areas and the vertical green space in commercial areas.(3)Sites attributes of three types of micro green space should be analyzed in aspects of site types,plane layouts,structures of green space and plant composition characteristics of plant community.3.A survey of 360 samples was conducted and analyzed concerning the spatial perception preference towards three types of micro green space in Tianhe Distrcit of high-density Guangzhou.On the basis of three preferences with the highest recognition,it is concluded that copious quantity,easy access and deep connection with daily life,are the core value of micro green space.The integrated model of the 5 dimensions contributes to the construction of high-density urban micro green space from the perspective of human needs,which also provides suggestions for micro green space of other types.(1)The three most important preferences in the perceived dimension towards the roadside green space are: “I support the city to save more room for roadside green space.(M=4.40,SD=0.656)”,“The roadside green space is close to where I live.(M=4.18SD=0.899)”and “The roadside green space serves as an important recreation place for neighborhood.(M=4.16,SD=0.836)”.(2)The three most important preferences in the perceived dimension towards the pedestrian-street green space are: “I often walk on the pedestrian street.(M=4.43,SD=0.544)”,“If weather,time and distance permit,I would like to walk on the pedestrian street or stop for a while.(M=4.25,SD=0.650)” and “I support more planning of the pedestrian street.(M=4.22,SD=0.780)”.(3)The three most important preferences in the perceived dimension towards the vertical green space are: “support for more urban vertical green space(M=4.41,SD=0.702)”,“more aesthetic perception of vertical green space(M=4.17,SD=0.791)” and “more aesthetic perception of vertical green space on the exterior fa?ade(M=4.07,SD=0.961)”.4.It is further verified in this paper that micro green space can regulate the urban microclimate through the measurement of ecological effects of three types of micro green space in Tainhe District of Guangzhou.(1)Under the conditions of different plant composition in roadside green space,the air temperature effect,according to the ecological effect at 14:00 in winter,is characterized by the trend of hard pavement > shrub – grass > arbor – grass > arbor – shrub – grass.It is suggested that plant composition should be chosen on the basis of the drop range of temperature.The effect of relatively humidity is expressed as: arbor – grass > arbor – shrub – grass > arbor – shrub – grass > hard pavement.For the reason above,it is determined by the weather condition whether to increase the humidity or not.The effect of illuminance manifests itself as: hard pavement > shrub – grass > arbor – grass > arbor > arbor – shrub – grass.Therefore,in light of the needs of plants and space function,proper blocking or illumination should be considered.The effect of air negative ions concentration is presented as: arbor – grass > arbor > arbor – shrub – grass > shrub – grass > hard pavement,and any species of plant that increases the concentration of negative ions is beneficial.(2)Under the conditions of different plant composition in the green space of pedestrian street,the air temperature effect,according to the ecological effect at 14:00 in winter,is characterized by the trend of hard pavement > greening street with arbors on both sides > greening street with arbors on one side > arbors – small arbors – shrubs,and suggestions are provided that plant composition should be chosen on the basis of the drop range of temperature.The effect of relatively humidity manifests itself as: hard pavement > greening street with arbors on both sides > greening street composed by arbors – small arbors – shrubs > greening street with arbors on one side.It is determined by the weather condition whether to increase the humidity or not.The effect of illuminance is presented as: hard pavement > greening street with arbors on one side > greening street with arbors on both sides > greening street composed by arbors – small arbors – shrubs,so moderate blocking or illumination should be considered.As for the air negative ions concentration,the effect is illustrated as: greening street with arbors on both sides > greening street composed by arbors – small arbors – shrub > greening street with arbors on one side > hard pavement,which shows that the concentration of negative ions will be even higher with more plants and greater canopy density.(3)In terms of humidity,illuminance and air negative ions concentration,it is found by the quantitative comparison between the vertical green space and bare wall that the temperature of vertical green spaces is obviously lower than that of bare walls.The vertical green space with the height of 1.5m,1m and 0.5m can reduce the temperature by 4.5℃,4.8℃ or 5.1℃ at most.Therefore,the vertical greening has a significant cooling effect with the increase of air temperature.In addition,the green space of this kind can maintain the wall temperature without sharp temperature difference in a day.The temperature difference in a day is 4.2℃,3.1℃,and 4.9℃,respectively,for vertical green spaces with the height of 1.5m,1m and 0.5m,while the difference is 6.8℃,6.1℃,and 7.1℃ for bare walls.As for humidity,the increase rate of vertical green spaces is 19%,23% and 21% with the height of 1.5m,1m and 0.5m,compared with bare walls.Besides,the illumination intensity of vertical green spaces can be reduced by 99.4%,and the concentration of negative ions in the environment can be improved by vertical green spaces.5.A design of vertical green space is proposed through the investigation and analysis of sites attributes,users’ perception and ecological effects of the three types of green space – roadside green space,pedestrian-street green space and vertical green space.Moreover,the design broadens the ideas of landscape architecture,which embodies the transition of views from art to function,then to environment,and integrates the ideas from aesthetics to science.6.Great importance has been attached to the system of micro green space from the concept of micro green space to the holistic view of urban forest construction,which covers the whole city by connecting a number of micro green space. |
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