Study On The Change Of Landscape Pattern In The Center Of Chengdu City

China's urbanization rate increased from 17.9% to 56.1% from 1978 to 2015,it is expected that China's urbanization rate will reach 72.9% by 2050.With population increase,the number and scale of cities are expanding,the natural and semi-natural underlying surface of the city is gradually replaced by the impervious surface,and artificial elements instead of natural elements become the basic characteristics of urban landscape changes in the global scope.At the same time,more and more cities are facing environmental pollution,resource shortages,traffic congestion and other ecological problems,which are closely related to human disturbance of the change of urban landscape pattern.This paper analyzed the change of landscape pattern within the third-ring road of Chengdu based on the three phases remote sensing image in1992,2002 and 2014 and the comprehensive use of landscape metrics.The representative plots of the study area were selected to study the species composition,and for beauty research by using the scenic beauty estimation(SBE).Then combined with natural factors and population economic data to discuss the driving forces of the change of urban landscape pattern in Chengdu city,it can reflect the human activities and environmental disturbance under certain social conditions.Get the following conclusion.(1)The area of buildings was on the rise in the past 22 years,and the proportion increased from 32.10% to 55.24%.The area of roads increased rapidly,and the proportion rose from 2.81% to 23.27%.On the contrary,the area of green space,cultivated land,water and other has trended down.The buildings had always been the type of matrix landscape in the region,and the area of buildings was mainly transformed from the area of green space,cultivated land and other.In the study area,the landscape pattern,which is mainly composed of buildings and green land,is transformed into the main structure of buildings and roads from 1992 to 2014.(2)From 1992 to 2014,the overall shape of integral landscape got increasingly complicated,the fragmentation degree increased,the Shannon's diversity index decreased from 1.56 to 0.63,the Shannon's evenness index decreased slightly but close to 1,which indicates that the landscape heterogeneity decreased,and the distribution is uniform and stable,this is the inevitable result of human disturbance in the landscape.(3)The population growth,the economic growth and policy were the main driving forces.The population growth was the main factor of the area of buildings and roads increased,the change of industrial economic structure was also an important factor of the change of landscape pattern.The instability of topography and climate also has a certain impact on the urban landscape pattern.The elimination of old plants,the ecological adaptability and growth of new plants and the artificial controllability of landscape design are also the factors that influence the change of urban landscape patterns.(4)There are 286 kinds of plant species on the park,the school and the monastery in the study area,among which the arbor is the main living type.Ginkgo biloba Linn.,Osmanthus fragrans(Thunb.)Lour.,Ficus virens Aiton var.sublanceolata(Miq.)Corner,Prunus cerasifera Ehrhart f.atropurpurea(Jacq.)Rehd.,Rhododendron simsii Planch.,Lagerstroemia indica Linn.,Gardenia jasminoides Ellis,Canna indica Linn.and Ophiopogon japonicus(Linn.f.)Ker-Gawl.are common garden plants in three plots.Toxicodendron vernicifluum(Stokes)F.A.Barkley,Sassafras tzumu(Hemsl.)Hemsl.,Euonymus fortunei(Turcz.)Hand.-Mazz.,Agave americana Linn.and Hosta plantaginea(Lam.)Aschers.are endemic to the park.Magnolia officinalis Rehd.et Wils.,Picrasma quassioides(D.Don)Benn.,Jasminum sambac(L.)Ait.and Ficus carica Linn.are endemic to the school.Ailanthus altissima(Mill.)Swingle,Robinia pseudoacacia Linn.and Buxus sinica(Rehd.et Wils.)Cheng are endemic to the monastery.(5)Select 71 representative pictures of the study area,and make a questionnaire to evaluate the beauty of the plant landscape in the study area.The results show that the highest value of the landscape photo number is 11,taken in Chengdu People's Park,its value is 10.99;the lowest value of photo number is 60,taken in Flowing Water Park of Chengdu,its value is 7.78.Plant color,plant landscape level,species,tree form and plant complete conditions have some impacts on the personnel evaluation scoring.It has some reference meaning for the future plant configuration mode by studying landscape plants and scenic beauty of plants landscape on the park,the school and the monastery within the third-ring road of Chengdu.A combination of qualitative and quantitative analysis of landscape pattern and driving force of Chengdu,in order to effectively reflect the status of landscape pattern and better understand the functions and connections between the urbanization and the landscape elements.So as to provide scientific basis and theoretical support for the urban planning.