基于能值理论的唐山市农业生态系统评价

农业生态系统是人类赖以生存的基本系统。为更好地评价区域农业生态系统的运行状况和变化特点，了解区域资源、环境和经济间的关系，选取唐山农业生态系统为研究对象，基于能值分析理论与方法，通过编制能值评价指标体系，对唐山市农业生态系统能值投入和产出状况、能值自给率、净能值产出率、人均能值用量、环境负载率和可持续发展状况进行定量评价。结果表明:唐山市农业生态系统整体运行较差，农业生态系统为消费型经济系统，可持续性有待提高；以农业用电、农机动力、柴油和化肥为代表的不可更新工业辅助能值投入逐年增加，使得农业生态系统能值产出率和可持续发展指数有一定下降趋势，且增大了对生态环境的压力。研究建议唐山市发展生态农业和现代农业，应着眼于拓展农业多功能性，逐渐改变传统农业生产方式，突出农业生态内涵，进而改变农业生态系统的能值投入和产出结构，促进其可持续发展。

Evaluation of Agricultural Ecosystems in Tangshan City Based on Energy Theory

Agricultural ecosystem is a basic system for human to live. The agricultural ecosystems of Tangshan City were studied to better evaluate the operation status and development characteristics of regional agricultural ecosystem, and understand the relationship between the regional resources, environment and economy. The quantitative evaluation of energy input and output, energy self-sufficient ratio (ESR), energy yield ratio (EYR), energy per person (EPP), environment loading ratio (ELR) and energy sustainability index (ESI) were investigated by compiling the system of energy evaluation index based on the theory and methodology of energy. The results showed that the overall operation of agricultural ecosystems of Tangshan City was poor, which was consumer-based economy system, and the sustainable development needed to be improved. The unrenewable industry supplemental energy inputs represented by the agricultural consumption of electricity, mechanical power, diesel oil and chemical fertilizer had been increasing year by year, which led to the energy yield ratio and energy sustainability index of agricultural ecosystem to have the downward trend, and caused the environment loading ratio to rise. These results suggest that ecological agriculture and modern agriculture should be developed in Tangshan City, and focus on expanding agricultural versatility. Additionally, in order to promote the sustainable development of agricultural ecosystem, it is essential to change the mode of traditional agricultural production gradually, to highlight the connotation of ecological agriculture, and to change the energy input and output structure.