Measuring sustainable development with the ecological footprint method——take Zhangye prefecture as an example
XU Zhong Min,CHENG Guo Dong,ZHANG Zhi Qiang (State Key Laboratory of Frozen Soil Engineering,CAREERI,CAS,Lanzhou 730000,China).
Humans consume the products and services of nature;every one of us has an impact on the earth.Does the human load stay within global carrying capacity?The ecological footprint concept has been designed to answer this question.The ecological footprint of any defined human population(from a single individual to a whole city or country)is the total area of ecologically productive land and water occupied exclusively to produce all the resources consumed and to assimilate all the wastes generated by the human population.The ecological footprint method presents a simple framework for national natural capital accountion. The ecological footprint is a function of population and per capital material consumption.The model assumes that all types of energy,material consumption and waste discharge require the productive or absorptive capacity of a finite area,and the calculation of the model requires incorporation of relevant income,prevailing values,social cultural factors and technology in the area under study.However,attempting to include all consumption items,waste types and ecosystem functions in the estimate would lead to intractable information and data processing problems.Estimating the ecological footprint of a defined population is a multi stage process.In this paper,we gather the multi stage model into following equation.EF=N·ef,ef=∑ni=1(aa i)=∑ni=1(c i/p i) The per capita footprint( ef )is the sum of land appropriated for each purchased goods( aa i) ,which is calculated by dividing average consumption of each goods( c i) by the average productivity of each goods( p i ),the population footprint can then be obtained by mulatiplying the per capital footprint( ef )by the population size( N ). Types of ecologically productive lands(mainly including arable land,fossil energy,residential area,pasture,forest)are addressed in detail. We calculated the ecological footprint of Zhangye prefecture in 1995.The ecological footprint ledger is composed of three main sections.The first ledger is basic biotic resources consumption including its sub products,the second ledger is energy consumption,the third ledger is trade balance,Trade balance through more detailed trade flow analyses can mitigate the influence of import and export product to consumption varies.Every particular on above ledger is presented from Table 1 to Table 5.Based on the ecological footprint concept and analysis framework,human consumption can be compared with natural capital production at the regional level using existing data.In the case of Zhangye prefecture,the ecological deficit of Zhangye is 0 346hm 2 per capita.Some simplification in calculation methodology results in over optimistic estimates.Some countermeasures to decrease ecological footpring such as increasing resources utilization efficiency,change consume pattern are put forward. The paper also analyses the advantages and disadvantages of the ecological footprint model.The ecological footpring present a simple framework for national and global natural capital accounting.Ecological footprint index is an excellent aggregate index that coonects many issues of sustainability,development and equity.The model reveals the extent to which local carrying capacity has been exceeded and allows a cumulative approach to impact analysis.The use of ecological productive area as a standard numeraire rather than money or energy,make the footprint easy to understand,and also permit provocative calculations. Integrated with encountered some main problems in this calculation,we also the weakness of overviewed the weakness of ecological footprint method.The limitations of the model are that it doesn't include several important issues :land areas lost to biological productivity because of contamination,erosion and urban“hardening” and dissertation(especially in northwestern of China).Methodologically,the assessments could be more complete by including the ecological spaces used for freshwater use,a particular important problem in arid area in northwestern of China.At the same ti