【作者】 易定宏；

【导师】 文礼章；

【作者基本信息】 湖南农业大学 ， 生态学， 2010， 博士

【摘要】 农业生态系统既有自然属性,又有社会属性,传统的比较优势研究方法主要是从经济学的角度,运用货币或者能量对农业生产比较优势进行评价。然而,纯粹货币评价方式受到越来越多非议,而能量分析又存在难以克服的缺陷。结合怀化市农业生态系统的实际情况,作者认为有必要开展针对农业生态系统的能值分析。能值分析方法与传统的经济学和能量学方法的主要差别在于,能值分析方法对自然资源和生物圈过程贡献的量化表达进行了考虑,在分析系统中加入了免费的环境源因素,更全面地考虑了系统过程对环境的影响。这既体现在主要资源和生物圈过程能值转换率的计算上,也反映在对具体能量系统的分析过程中。在理论上,能值分析提供了比较和衡量不同生态流的共同尺度与综合分析方法,为生态经济系统开辟了定量分析研究的新方法,有助于协调生态环境与经济发展。本文在以下方面做了研究：编制怀化市农业生态系统能值分析表,并建立怀化市农业生态系统能值分析指标体系(如净能值产出率、能值投资率、环境负载率等)。通过对系统的演变趋势做出适当的判断,辨识怀化市农业生态系统发展的趋势,并对本地区农业生态系统可持续性进行定量分析评价.选取1980-2008年作为时间序列,对27年来怀化市农业生态系统能值趋势与演替轨迹作进一步的研究,探求怀化市农业生态系统结构与功能变化的规律,预测其发展趋势。在以下方面做了重点研究：本文将农业视为自然生态系统与社会经济系统的有机结合。运用国际前沿的能值理论及其分析方法对整个系统进行科学评价,将自然生态系统对农业的作用与社会经济对农业的作用综合分析,对农业生态经济系统的分析和认识又深入了一层。基于能值分析,建立比较优势模型,以怀化市不同农业生态典型县域的农业生态系统作为案例分析。结果表明,新拓展的能值比较优势指标能够更科学、更全面的评价农业生态系统的比较优势,为农业生态经济系统科学合理的发展提供指导。研究的对象更加具体,更加深入。能值研究对象大多数是大农业生态经济系统,对单个具体作物系统进行研究填补了能值研究的空白。而目前比较优势的研究也是以全国或跨省区来进行的,对县域尺度进行研究的例子还很少见。对大农业进行研究的弊端就是容易忽略不同农作物及地域差异,会造成认识上的片面。本研究考察不同作物不同县域,是对能值研究的深入表现。最后得到的结论如下：怀化市典型县域沅陵、中方、会同水稻系统的净能值产出率排序为中方(34.11%)>沅陵(29.74%)>会同(23.98%)>怀化市(15.27%),中方位于第一。究其原因,是因为在水稻生产过程中,购买能值投入较低,而索取的无偿自然资源能值较高。水稻作物系统净能值产出率小于1,说明其投入产出不合理,经济效益不高。怀化市不同农业生态区典型县域沅陵、中方、会同水稻系统的能值投入率排序为怀化市(11.41)>沅陵(8.35)>中方(5.75)>会同(3.40)。会同的能值投入率最低,怀化市最高。表明会同水稻作物系统每单位自然环境资源的利用投入了较少的购买能值,生产成本较低,环境压力较小,具有较强的市场竞争力。玉米净能值产出率的排序为中方(239.48%)>会同(228.39%)>沅陵(218.59%)>怀化市(172.66%),中方和会同值产出率较高,而怀化市产出率低,说明玉米作物生产过程购入了较多的购买能值,生产成本较高,市场竞争力较弱。怀化市农业生产系统能值投入水平较高,环境压力较大,能够较大规模进行现代化农业建设,运用现代化农业手段和先进的农业经营理念,依托自然环境优势,优化系统运转结构功能效率,提高能值产出效率。通过怀化市能值投入比例分析可以看出,工业辅助能投入大于可更新有机能投入,增加有机能值的投入,可提高农业经济效益。通过怀化市农业生态系统演变趋势我们可以看出,农业生态经济效益不断提高。这是由于怀化市增加了工业辅助能值的投入,系统能值投入结构区域合理。这意味着怀化市正摆脱落后的农业生产方式,向现代化农业迈进。更多还原

【Abstract】 Agricultural ecosystem has both natural attributes and social attributes; the research method of traditional comparative advantage theory mainly evaluates the comparative advantages by using currency or energy from the angle of economics. However, the pure currency evaluation method causes more and more criticism, while the energy analysis has defects which are difficult to overcome. In consideration of the actual agricultural ecosystem in Huaihua, the author holds that it is necessary to conduct energy analysis on agricultural ecosystem.For energy analysis method, its main difference with the traditional single method of economics and energetics lies in its quantification expression of the natural resources and biosphere process contribution; it adds free environment-s ource elements to the analytic system and takes into consideration the influence on the environment caused by system process in a more complete way. This comprehensive consideration is not only reflected in the calculation of energy t ransformation rate of main resources and biosphere process, but also in the ana lysis process of the specific energy system.In terms of theory, energy analysis provides a common standard and comprehensive analysis method for measuring and comparing various ecological flows and develops a new approach of quantitative analysis research for ecological-economic system, which helps coordinate ecological environment and economic development.This study has performed the general researches into the following:Developing the energy analysis table of agricultural ecosystem of Huaihua, and establishing the index system of energy analysis for agricultural ecosystem of Huaihua (such as net energy output rate, energy investment rate, environment load rate, etc.). It identifies the development trend of the agricultural ecosystem of Huaihua through making a proper judgment on the evolution trend of the system, and also conducts a quantitative analysis evaluation on the sustainability of agricultural ecosystem in this region.For the analysis of energy evolution of agricultural ecosystem, the years between 1980 and 2008 are chosen as the time series, and a further study on the energy trend of the agricultural ecosystem and its succession track in Huaihua for 27 years has been conducted to explore the law of the agricultural ecosystem structure and changes of function in Huaihua and to predict the future development trend of the system.This paper mainly focuses on the following areas:This paper regards agriculture as a combination of natural ecosystem and socio-economic system. By adopting internationally advanced energy theory and methods to carry out scientific evaluation to the whole system and by making comprehensive analysis on the contribution of natural ecosystem made to agriculture and the contribution of socio-economics made to agriculture, we have made a step forward in the analysis and understanding of agricultural ecosystem.A comparative advantage model is built based on energy analysis and the agricultural ecosystem in the typical counties in Huaihua with different agricultural ecosystems is analyzed as case study. The analysis result shows that the newly developed energy comparative advantage index can measure the evaluated agriculture in a more complete and scientific way and provides a guidance for the scientific and reasonable development of the agricultural ecosystem.The objects of the study are more specific and profound. Most objects of the study belong to the macro-agricultural ecosystem and the research into single specific crop system fills in the gap of energy study. Now the study of comparative advantages is conducted on a national or provincial basis, and there are very few cases of study based on county dimension. The drawback of the macro-agriculture study is that the differences between different crops and regions are easily ignored, thus causing the one-sidedness in understanding. This study investigates all different crops in different counties and is an in-depth representation of energy study.The final conclusions are as follows:The net energy output rate in rice system in the typical counties:Yuanling, Zhongfang, Huitong in Huaihua City ranks in the following way::Zhongfang (34.11%)> Yuanling (29.74%)> Huitong (23.98%)> Huaihua (15.27%). Zhongfang ranks the first, and the reason is that, in the process of rice production, the investment in buying energy is low, while the free energy of natural resources is high. When the net energy output rate of rice system is less than one, it shows that the input and output is not reasonable and the economic benefits are not favorable.The net energy input rate in rice system in the typical counties:Yuanling, Zhongfang and Huitong in different agricultural ecological areas in Huaihua ranks in the following way:Huaihua (11.41)> Yuanling (8.35)> Zhongfang (5.75)> Huitong (3.40).Huitong enjoys the lowest energy investment rate while Huaihua enjoys the highest. It shows that less purchased energy is utilized in the usage of free environment resources of per unit of rice in Huitong; so the rice system is low in production costs, exerts less pressure on the environment and hence is more competitive in the market.The energy output rate for corn ranks in the following way:Zhongfang (239.48%) > Huitong (228.39%)> Yuanling (218.59%)> Huaihua (172.66%). The energy output rates of Zhongfang and Huitong are high, while that of Huaihua is low, indicating that more energy is purchased in the production of corn crop in Huaihua, so its production cost is high and is weak in competition in the market.The agricultural production system of Huaihua City is high in energy inve stment and in pressure on the environment, so a large-scale modern agricultural construction can be carried out; by using modernized agricultural methods and advanced agricultural business ideas and supported by the advantages of natur al environment, the functional efficiency of the system operation structure can be optimized and hence the energy output rate can be improved.From the analysis on the energy input proportion in Huaihua City, we can see that the input of industrial supporting energy is higher than the input of organic energy; so the increase in input of organic energy will improve the ec onomic benefits of agriculture.From the evolution of agricultural ecosystem in Huaihua City, we can see that the agricultural ecological economic benefits improves continuously. This is thanks to the increase in the investment of industrial supporting energy by Huaihua City, so the investment structure of the system energy is more reasonable. This means that Huaihua City is breaking away from backward production methods and is advancing towards a modernized agriculture.更多还原