Emergy evaluation on the sustainability of cropping-grazing system in economic belt on northern slope of Tianshan Mountains
基于能值的天山北坡经济带农牧系统可持续性评估

By the methods of emergy analysis,this paper evaluated the eco-economic system of cropping-grazing in the economic belt on northern slope of Tianshan Mountains.A suit of emergy indices was adopted to quantitatively assess the emergy flows.The results showed that environmental resources made a great contribution to the cropping-grazing system.The emergy of environmental resources occupied 79.2% of the total,and the net emergy yield rate was 4.81,which were much higher than the mean values(13% and 0.27)of the whole nation and illustrated that the cropping-grazing system in this area possessed a certain competitive advantage in its production.The macroeconomic value of the cropping-grazing products was much higher than their market value,due to the large input of 'free'resources from the environment to the cropping-grazing production.The value of environmental loading rate was 0.373,which was far below the national average of 2.8 and indicated a less pressure on the environment.The emergy sustainability index was 12.90,showing a good development potential of this system.Some measures about the industrial structure adjustment were proposed for promoting the sustainable development of regional agriculture.