基于能值分析的深圳市三个小型农业生态经济系统研究

应用能值分析方法,通过能值转换率,把深圳市3个农场生态经济系统的能量流、物质流、货币流和信息流转化为统一量纲———能值。在绘制能值系统概图和编制能值分析表的基础上,建立能值评价指标体系对3个系统的能值输入结构、生产效率、环境负载和可持续发展状况等进行分析和比较。此外,比较经济指标与能值分析结果,并采用情景分析对农场未来发展做出预测。能值分析方法不仅考虑环境及其服务功能对经济生产的贡献,同时能值交换率和能值产出率把系统经济流入和产出纳入分析过程,结合环境和经济评价,可用于综合分析农场生态效益和经济效益。研究结果表明:西丽果场是可持续发展能力最高的农场,碧岭现代农业科技园次之,而山海农场的可持续发展能力最低。都市农场应该大比例利用可更新资源,努力发展农业生产,并且积极提升农业的技术含量。在此基础上,控制规模合理地发展旅游经济,走高科技农业生态旅游之路。

Research on three small-scale agricultural ecological-economic systems in Shenzhen City based on emergy analysis

The ability to transform different types of resource flows in energy, physical, capital and information into a unified standard-emergy-makes emergy analysis is an appropriate tool for evaluating and comparing the structural characteristics of input, production efficiency, environmental load, economic viability and the overall sustainability of agricultural ecological-economic systems. The systems studied were Biling Modern Agricultural Technology Park (Biling Park), Xili Orchard and Shanhai Farm in Shenzhen, China. Based on a general emergy system diagram and emergy analysis table, we constructed an emergy evaluation system to analyze and compare these three farms. As for emergy input structure, Xili Orchard mainly relied on renewable resources, which accounted for 50.2% of its total emergy input; Biling Park and Shanhai Farm depended mostly on purchased nonrenewable input. Xili Orchard had the lowest environment load ratio (ELR) value because of its relatively high renewable resources input and low level of purchased nonrenewable resource input. Unlike Xili's situation, Shanhai Farm's ELR value had the highest ELR because of its relatively low level of renewable resource input and high level of purchased nonrenewable resource input. The emergy indices for sustainable development (EISD) value were 12.70, 2.47, and 0.52 for Xili Orchard, Biling Park and Shanhai Farm, respectively. Although Shanhai Farm had a relatively high emergy exchange ratio (EER), strong pressure on the environment limited its sustainability. Also, we compared the economic index analysis with emergy analysis and found them to be consistent with each other. Xili Orchard had the highest economic output/input ratio and benefits density, while Shanhai Farm had the lowest values. The results show Xili Orchard was the most efficient system and Shanhai Farm was the least efficient system from both economically and ecologically. We then used scenario analysis to predict how the three farms would develop in the next ten years. The outlook for Biling Park gives it a bright future and an enormous potential for development. However, if the Shanhai Farm continues expanding its tourism resources blindly without making an effort to develop basic agricultural production, its pressure on the environment would continue to increase, preventing it from achieving sustainability. Xili Orchard was the most sustainable, followed by Biling Park and Shanhai Farm as least sustainable. Emergy analysis was found to be an efficient method for evaluating ecological and economic benefits of these farms, because it not only accounted for the environment's support and contribution to these agricultural systems, but also linked the environment and economic evaluation with the Emergy Exchange Ratio (EER) and Emergy Yield Ratio (EYR). Emergy analysis is a bridge between economics and ecology. Emergy analysis will help show managers of city farms they should strive to make the best use of renewable resources which will facilitate agricultural production; city farms should also actively incorporate high technology agriculture into their operations and understand the scientific system standards. They can then develop tourism rationally. In summary, city farms should seek out new agricultural systems which combine high levels of technology and with ecological tourism.