Assessment Of Ecological Environment And Measurement Of Ecological Efficiency In Beijing

Based on the analysis of land use and normalized differential vegetation index in Beijing,this paper evaluated the status and changes of ecological environment in 2000,2005,2010 and 2015.Finally,the general DEA and super-SBM models were used to calculate the ecological efficiency of Beijing.The results showed that:(1)The monthly and seasonal mean values of NDVI,precipitation and average temperature in Beijing increased first and then decreased.The monthly average of DVI from July to September is higher,and the monthly average from January to March is lower.The maximum monthly average is 3.47-4.48 times of the minimum.The average value of NDVI in the second and third quarters was higher,followed by the first quarter,the lowest was the fourth quarter,and the maximum value was 2.82-3.03 times of the minimum.NDVI had a high correlation with mean temperature and a high positive correlation with precipitation.(2)According to the actual number of four years in Beijing,the index of ecological and environmental conditions were 56.91,59.46,60.41 and 59.69,respectively,and the ecological and environmental conditions are good;according to the equivalent number of in Beijing,the index of ecological and environmental conditions were 54.30,57.99,59.44 and 57.99,respectively.In 2000,the ecological and environmental conditions was general,and the other three years were good.Beijing had high vegetation coverage and rich biodiversity,which was more suitable for human life and living.(3)From 1981 to 2017,Beijing's technology,pure technology and scale efficiency were 0.81 8,0.986 and 0.828,respectively,and the overall ecological efficiency was relatively high.Only technology and scale efficiency were effective in 1982 and 2017,and ecological inefficiency was caused by scale efficiency.The average value of Beijing's output shortage was 2.822 billion yuan RMB,and other input indicators were redundant except the total water consumption.Energy consumption and industrial solid waste were still the main problems restricting the sustainable development of Beijing.(4)The calculation of super-SBM showed that,the ecological efficiency of Beijing was 0.9451,the maximum was 1.3620 in 2017 and the minimum was 0.4991 in 1994.Beijing's output was less than 16.915 billion yuan RMB,and all input indicators were redundant.Super-SBM model can rank several relatively effective decision-making units,which was convenient for comparing the results of efficiency measurement.It was a method of efficiency measurement worth popularizing.