Lanzhou Urban Ecosystem Study

Urbanization is a certain result of human technique progress,economic development and society civilization . Urban system is a reuniting system of urban ecosystem and urban economic system. Only if we study the city as a whole ecosystem and completely analyzing the systems structure ,function and if s coordination,we could find out the key and defects to improve the efficiency of the ecosystem,and then we could use all kind of resources to realize the city's sustainable development. Urban ecology is a new project which was studied for a long time in the abroad and be going deep in our country. The system analysis is the key of what urban ecology study and was carried throng six step. With sustainable development as target,the city's development condition was analysed by the geography and physiognomyx resources condition,industry structure,energy structure,population quantity and quality,etc . Compared with LanZhou and other cities ,LanZhou is faced to severe challenge,especially in the field of entironment,now LanZhou has been one of the "famous" cities at home and abroad which are serious in air pollution aspect. Setting up index system follow five principles including synthesis,representative,gradation,contrast,operation. Gradation analysis is adopted in setting up index system of the city's ecology support system ,then first-degree index is composed of structure,function and coordination. According to discussed selecting principle of appraisal index,second-degree index is made up several factors,and on the basis of second-degree index,third-degree index forms the whole appraisal index system by selecting several factors. Terfir method is adopted by weight of first-degree and second-degree index,generally it is divided into two or four rounds. Analysing index at different levels,LanZhou's ecology is still at a very low level .It's main problem is irrational city's structure and bad cycle use and inefficiency of energy. Devote major efforts to developing forest,grass,vegetation and city's greenbelt,strictly control air pollution,water pollution and noise pollution,push on LanZhou's sustainable development.