摘要:能值方法是美国生态学家H.T.Odum在20世纪80年代创立的生态经济系统分析方法，近年来被广泛应用于农业系统分析当中。但是，目前已发表的大量论文中对于能值评价过程中的重要细节常会出现不同的处理方式，造成评价结果不确定性增加、可比较性降低，影响了能值评价方法在农业研究领域的深入应用和发展。因此，本研究梳理了国内外农业生态系统能值研究的基本概况，并总结了相关研究中常见的五大问题，包括：全球能值基准变化所引发的能值转换率选择混乱问题、农业生态系统评价边界界定的问题、农业生产过程环境资源贡献的不合理计算问题、农业生态系统投入资源的分类问题和系统能值投入与产出不守恒问题。在此基础上，基于我们目前的认识提出了相关问题的解决思路：第一，规范能值评价中的能值转换率（UEV）参数的选择原则；第二，基于“四维时空尺度”标准界定系统边界；第三，构建公式合理体现土壤、农业用水在农业系统能值分析中的能量贡献；第四，基于农业生态系统能值常用指标设定4组标准规范农业生态系统投入资源的分类；第五，遵循能值代数规则保证能值守恒。通过以上分析，以期引起广大学界的讨论和批评，共同促进能值方法在全球农业系统分析中的规范化应用。
关键词:能值评价/
农业生态系统/
能值转换率/
系统边界/
环境资源贡献/
投入资源/
投入-产出守恒
Abstract:Emergy evaluation (EME) is an extensively used method for the assessment of ecological economic systems which has been applied in a diverse array of fields, with more recent application in agricultural systems. However, despite an increasing number of studies using the EME approach to assess agricultural systems, some of the evaluation principles of EME have been misunderstood by researchers applying the method resulting in unreliable assessments. Therefore, this study aimed to investigate issues identified from prior research using EME in the assessment of agricultural systems. Five common problems were identified: 1) disordered selection of unit emergy values (UEV) caused by updated global emergy baselines, 2) incomplete definition of system boundary, 3) arbitrary calculation of emergy contribution derived from environmental resources, 4) inoperable classification of system inputs, and 5) non-conservation between input and output emergy in agricultural systems. Concurrently, we proposed related solutions for resolving the identified problems which included: standardizing the selection principle of UEV in the EME; defining system boundary based on a standard of 'four-dimensional space-time scale'; constructing formulas to reasonably reflect energy contributions from soil and water for agricultural production in the EME; setting four standards to order the classification of input resources of agricultural systems; and applying the emergy accounting algebras to ensure the emergy conservation in research. We hope that our research will initiate further discussions on approaches to EME assessment in agricultural practices thus promoting a more standardized application of the emergy method in future studies.
Key words:Emergy evaluation/
Agricultural ecosystem/
Unit emergy value/
System boundary/
Environmental energy contribution/
Input resources/
Emergey conservation between input and output
PDF全文下载地址:
http://www.ecoagri.ac.cn/article/exportPdf?id=a8421123-6f02-4bf5-b7af-73241027e010
