Study Of Plant Performance&Disposition Of Roof Greening Projects In Beijing And The Ecological Benefits Of Green Roofs

From 2011 to 2015,it is China's 12th Five-Year Planning Stage,which is for national economy and social development.The rapid growth has many "side effects",the urban environment problem hinders the urban sustainable development,at the same time,endanger the physical and mental health of urban residents.In 2008,the government launched a large scale of "flat-to-slope" roof reformation engineering.However,the "flat-to-green" is much more healthier from not only the perspective of ecological benefits but also urban sustainable development."Flat-to-green" means greening on flat roofs,which is called "roof greening".The study of plant performance and disposition is based on the plant investigation of roof greening projects in Beijing.It was focused on three aspects:species,performances and aesthetic perception.First,choose 3 typical cases of each type of roof greening projects;then,comparative analysis and conclusion on investigations;after that,consulted the problems and influencing factor of the selection of plants with experts,as well as project rating.At last,summarized the main influencing factors,selection principle and disposition essentials of plants in roof greening,and recommended plant species in Beijing city.The study of ecological benefits of roof greening has three parts:(1)the storage capacity of water of plant medium;(2)the thermal radiation effect of different materials;(3)the ecological-economic benefits of green roofs.(1)The storage capacity of water of plant medium:Through the experimental quantitative measurement to find out the storage capacity difference between inorganic plant medium which commonly used in roof greening and soil which commonly used on underground garage rooftop.The research results can provide references for irrigation water consumption of roof greening,and for urban green building planning,and also to prove the positive effect of roof greening in alleviating the pressure of urban rain and flood.(2)The thermal radiation effect of different materials:On a sunny summer day,monitoring the changes in the day of heat radiation values of plants,water,pavement and facilities of different materials through thermal imager.The study found that the material,orientation,area,surface texture or the small environment of the monitoring objects can cause the difference of temperature change range and speed.The research shows that roof greening has a positive effect on reducing heat radiation,reducing atmospheric environment temperature and alleviating the urban heat island effect.(3)The ecological-economic benefits of green roofs:Based on Beijing landscaping quantitative evaluation for the ecological benefit' software,input plant data of different types of roof greening cases,resulting in economic benefits of comprehensive ecological benefits by carbon sequestration,release oxygen,absorption of heat and dust.The purpose of the research is to provide a reference for the healthy and sustainable development of roof greening in Beijing.