Study On The Shading Effect Of Common Street Trees In The Main Urban Area Of ??Chongqing

With the substantial increase of motor vehicles in the rapid developed cities,automobile exhaust and environmental pollution have directly caused the rising of city temperature.People's life was influenced more and more by outdoor thermal environment,so the demands for better and comfortable environment become more and more urgent.Plant greening plays an important role in improving road thermal environment quality,resisting solar radiation,reducing air temperature,creating a pleasant space environment and improving the comfortable of pedestrian.However,the traditional plant landscape is more embodied in the"scene"and"view",pursuing for being delightful in form and ignoring that plants can intuitively improve the practicality of thermal environment.In road landscape design,improvement function of greening for thermal environment is less considered.Through comparing the measured temperature on the main road of Chongqing City with the temperature published at the meteorological station,the author found that the measured temperature of the road where the vegetation grew well and which formed good shade environment was obviously lower than that published by the meteorological station;While the measured temperature of the road where the vegetation grew worse and which didn't form good shade environment was much more severe than that published by the meteorological station;therefore,road landscape needs to consider the design of plant shade.As the main body improving thermal environment in greening,arbor plays a role in resisting solar radiation,reducing temperature and improving the quality of outdoor thermal environment through shading.For a long time,systematic research on arbor's shading effect has been absent and reasonable evaluation index for its shading effect has been absent.In view of the above deficiencies,the author carried out the researches as follows:Firstly,this paper analyzes the shade effects of different space plants,shade effects of trees and AHP evaluation system.Secondly,this paper conducted investigation and statistical data analysis on the border trees of the main urban area of Chongqing City.According to field investigation,enquiry,generalization and other methods,the current application situations of the main border trees of 107 roads in the main urban area of Chongqing City have been investigated,including varieties,living habits,ornamental characteristics,growth condition and arbor size.Conduct statistics of common shading border trees in the main urban area of Chongqing City and finally determine that taking Ginkgo biloba L.in Jintong Road,Magnolia grandiflora L.in Longqing Road,Salix babylonica in Qixia Road,Livistona chinensis(Jacq.)R.Br.in Keyuan Six Road,Caryota ochlandra Hance in Keyuan Second Street,Bischofia polycarpa(Levl.)Airy Shaw and Erythrina variegata Linn.in Keyuan Fourth Road,Cinnamomum japonicum Sieb.in Huying Street,Bauhinia purpurea L.in Wenchang Road,Cinnamomum septentrionale Hand.-Mazz in Ruitian Road,Platanus orientalis L.in Huangyang Road,Elaeocarpus decipiens Hemsl.in Jialing River Shore Road,Ficus virens Ait.var.sublanceolata(Miq.)Corner in Fuhua Road,Koelreuteria paniculata Laxm.in Baosheng Avenue and Ficus concinna(Miq.)Miq.in Longhuai Street as the main research objects of this paper.Then,implement experimental research and analysis on the chosen research objects,simultaneously measure and calculate rate of temperature drop,shading rate,shadow quality,shadow area and effect of shade of the border trees and rank them.It is calculated the cooling rate from high to low as follows,_Bischofia polycarpa(Levl.)Airy Shaw.?Erythrina variegata Linn.?Cinnamomum japonicum Sieb.?Bauhinia purpurea L.?Koelreuteria paniculata Laxm.?Caryota ochlandra Hance?Ginkgo biloba L.?Ficus concinna(Miq.)Miq.?Ficus virens Ait.var.sublanceolata(Miq.)Corner.?Livistona chinensis(Jacq.)R.Br.?Cinnamomum septentrionale Hand.-Mazz?Salix babylonica.?Platanus orientalis L.?Elaeocarpus decipiens Hemsl.?Magnolia grandiflora L.It is calculated the shading rate from high to low as follows,Ficus virens Ait.var.sublanceolata(Miq.)Corner?Bauhinia purpurea L.?Livistona chinensis(Jacq.)R.Br.?Koelreuteria paniculata Laxm.?Ficus concinna(Miq.)Miq.?Erythrina variegata Linn.?Cinnamomum septentrionale Hand.-Mazz?Bischofia polycarpa(Levl.)Airy Shaw?Magnolia grandiflora L.?Cinnamomum japonicum Sieb.?Platanus orientalis L.?Elaeocarpus decipiens Hemsl.?Salix babylonica?Ginkgo biloba L.?Caryota ochlandra Hance.It is listed the shadow quality from high to low as follows,Bischofia polycarpa(Levl.)Airy Shaw?Erythrina variegata Linn.?Cinnamomum japonicum Sieb.?Bauhinia purpurea L.?Koelreuteria paniculata Laxm.?Ficus concinna(Miq.)Miq.?Ginkgo biloba L.?Ficus virens Ait.var.sublanceolata(Miq.)Corner?Livistona chinensis(Jacq.)R.Br.?Caryota ochlandra Hance?Cinnamomum septentrionale Hand.-Mazz?Salix babylonica?Platanus orientalis L.?Elaeocarpus decipiens Hemsl.?Magnolia grandiflora L.It is listeed the shadow area from high to low as follows,Cinnamomum septentrionale Hand.-Mazz?Koelreuteria paniculata Laxm.?Bauhinia purpurea L.?Cinnamomum japonicum Sieb.?Bischofia polycarpa(Levl.)Airy Shaw?Ficus virens Ait.var.sublanceolata(Miq.)Corner?Elaeocarpus decipiens Hemsl.?Erythrina variegata Linn.?Ficus concinna(Miq.)Miq.?Magnolia grandiflora L.?Ginkgo biloba L.?Platanus orientalis L.?Caryota ochlandra Hance?Salix babylonica?Livistona chinensis(Jacq.)R.Br.It is calculated the shade effect from high to low as follows,Bauhinia purpurea L.?Koelreuteria paniculata Laxm.?Cinnamomum japonicum Sieb.?Bischofia polycarpa(Levl.)Airy Shaw?Erythrina variegata Linn.?Cinnamomum septentrionale Hand.-Mazz?Ficus virens Ait.var.sublanceolata(Miq.)Corner?Ficus concinna(Miq.)Miq.?Ginkgo biloba L.?Elaeocarpus decipiens Hemsl.?Caryota ochlandra Hance?Salix babylonica?Platanus orientalis L.?Livistona chinensis(Jacq.)R.Br.?Magnolia grandiflora L..Besides,the research found that all the relationships between the cooling rate,shading rate,shadow quality,shadow area and shade effect of the border trees obey the normal distribution.Wherein,the rate of temperature drop,the shadow quality and the shadow area present positive correlation relationships with the effect of shading while the shading rate presents a negative correlation relationship with the effect of shading.Finally,use of the evaluation trees shade effect model is established by AHP,to calculate and level sorting and consistency check the weight value of the selected evaluation factors,the evaluation equation,the measured results of the equation into the trees shade effect evaluation.It is calculated the shade effect from high to low as follows,Bauhinia purpurea L.?Koelreuteria paniculata Laxm.?Cinnamomum japonicum Sieb.?Bischofia polycarpa(Levl.)Airy Shaw?Erythrina variegata Linn.?Cinnamomum septentrionale Hand.-Mazz?Ficus virens Ait.var.sublanceolata(Miq.)Corner?Ficus concinna(Miq.)Miq.?Ginkgo biloba L.?Elaeocarpus decipiens Hemsl.?Caryota ochlandra Hance?Salix babylonica?Platanus orientalis L.?Livistona chinensis(Jacq.)R.Br.?Magnolia grandiflora L..Among them,Bauhinia purpurea L.belongs to a grade 1,Koelreuteria paniculata Laxm.?Cinnamomum japonicum Sieb.?Bischofia polycarpa(Levl.)Airy Shaw?Erythrina variegata Linn.?Cinnamomum septentrionale Hand.-Mazz belongs to grade 2,Ficus virens Ait.var.sublanceolata(Miq.)Corner?Ficus concinna(Miq.)Miq.belongs to grade 3,Ginkgo biloba L.?Elaeocarpus decipiens Hemsl.?Caryota ochlandra Hance?Salix babylonica?Platanus orientalis L.?Livistona chinensis(Jacq.)R.Br.?Magnolia grandiflora L.belongs to grade 4.Using the analytic hierarchy process(AHP)and the measured calculation method to evaluate the shade effect of roadside trees reach the same conclusion.This paper starting from the practicality of border trees,explored the shading effect of common border trees in the main area of Chongqing City.It aimed to lay a basis for build a complete and huge database of tree shading effect.Moreover,it will provide more scientific guidance and reference function for future road landscape design and research.