中国粮食供求区域均衡变化研究：模型构建与模拟分析

【作者】 梅燕；

【导师】 陆文聪；

【作者基本信息】 浙江大学 ， 农业经济管理， 2008， 博士

【摘要】 中国粮食在20世纪90年代中后期就已实现了从长期短缺到总量基本平衡、丰年有余的历史性转变,但随着中国经济持续高速增长,农村工业化与城镇化进程不断加快以及农业市场化与国际化程度的不断提高,影响中国粮食供求均衡格局的国内外环境和主要因素发生了重大变化。粮食播种面积不断缩减而粮食单产提高缓慢,使得粮食持续增长潜力受限;人口刚性增长,居民食物消费结构升级,使得粮食饲料粮和工业消费需求不断增加;同时由于国际市场粮食供求偏紧,世界粮食库存不断减少,使得粮食进出口贸易压力增大。这些导致了近些年来中国国内产需缺口不断扩大,部分省区粮食供求失衡加剧,特别是2007年初以来世界范围内的粮食价格全面上涨,引发了人们对中国粮食安全问题的新一轮担忧,中国未来是否会出现全国性、区域性粮食短缺,已成为当前政界和学术界的中心议题之一。尽管2004年以来中国粮食生产出现了重要转机,但粮食生产尚未得到有效恢复,制约粮食安全的深层次矛盾并没有消除。当前有关中国粮食供求均衡问题的研究结果多是定性模糊判断,而部分采用数量模型分析的研究结论也主要集中在20世纪90年代中后期,对中国加入WTO后的粮食供求均衡问题关注较少,尤其缺乏具体定量的实证数据分析,且有关中国粮食供求区域均衡问题的研究尚不多见。因此,突破现有研究局限,利用数量经济学模型定量分析和研究新形势下中国粮食生产、消费和贸易条件变动的关键因素对中国粮食供求区域均衡格局的影响效应,探讨中国粮食供求区域市场均衡内在机理,预测中国粮食供求格局状况,对在工业化与城镇化发展进程中把握中国粮食供求区域均衡格局变化趋势,采取有效的农业政策措施,确保全球化背景下中国国内粮食安全,具有十分重要的现实价值和理论意义。本文在对国内外有关中国粮食供求均衡问题研究成果进行系统全面综述的基础上,首先利用中国国内31个省区粮食供求面板数据,分别从全国和省区两个层次上量化分析了中国近30年粮食生产、消费和贸易历史变化情况;并基于空间计量经济学理论与方法,运用Panel Data结合空间误差模型,着重从粮食自然与生产条件、粮食生产技术与效益因素、人口与区域发展因素以及粮食政策因素四个方面实证研究了导致中国粮食供求格局变化的主要原因,在此基础上归纳总结并分析了当前影响中国粮食供求区域均衡的关键问题。实证结果显示:中国粮食生产总量虽暂时能够满足国内需求,但供求格局在中长期仍处于紧平衡状态,且省区间粮食供求差异显著;而除了自然条件与技术经济因素,人地关系、劳动力报酬和非农就业是影响中国粮食供求区域格局变化的关键因素,同时一些新的影响因素影响了粮食供求均衡的变动,如生物能源的兴起改变了粮食消费需求结构,农村劳动力跨区域流动加剧了粮食主销区供求失衡程度,国际与国内市场紧密的联系影响了粮食价格的波动。因此目前中国粮食生产已逐步向农村劳动力报酬较低、农民家庭非农业收入占总收入比例较小和人均耕地资源相对丰富的经济相对不发达地区转移和集中,粮食生产发展潜力有限;随着粮食的消费需求持续刚性增长,同时由于国际粮食市场的负面影响不断增大,使得当前中国粮食供求均衡格局面临国内外环境变化的双重挑战。其次,本文基于国际学术界广泛采用的“多市场、多区域局部均衡模型”理论与结构,将中国粮食问题纳入全球粮食市场体系当中,以稻谷、小麦、玉米、大豆、薯类、其他杂粮等6种主要粮食产品为主要研究对象,构建了共涉及18种(类)主要农产品和将中国各省区与世界其他国家划分为57个区域的“中国——世界农业区域市场均衡模型(Chinese World Agricultural Regional MarketEquilibrium Model,简称CWARMEM)”,该模型包含生产供给、消费需求、价格转移和均衡条件四大模块,涉及37组矩阵共10791个数学方程式;并在GAMS软件系统中构建了1029行程序代码。随后,在分析和归纳当前影响中国粮食供求区域均衡的主要因素的基础上,设计了“城镇化与工业化进程导致耕地资源减少”、“粮食生产水资源利用变化”、“粮食生产技术进步”、“人口自然增长”、“农村劳动力跨区域流动”、“经济增长过程中城乡居民收入提高引起的食品消费结构变化”、“国内粮食生产者直接补贴政策变化”、“生物乙醇燃料应用引发的粮食需求变化”和“人民币汇率升值”等9种关键情景方案,并利用所构建的CWARMEM模型进行了实证模拟分析,展示并比较研究了不同情景下中国粮食在生产、消费和贸易方面的各种模拟结果,并据此从全国和区域两个层次进一步提出了有关政策启示。CWARMEM模型模拟分析结论表明:(1)粮食自然以及生产条件变动影响粮食综合生产能力的提高。随着粮食主产区经济发展速度的加快,尤其是工业化和城镇化进程的不断推进,这些省份粮食播种面积的减少将会使得中国整体粮食产量的增幅受限;而增加西部耕地资源丰富但干旱地区的有效灌溉面积以及增加农业科技投入和推广人员则有利于提高粮食单产,保证粮食产量稳定;同时加大对国内粮食主产区的粮食生产者补贴力度明显有利于提高国内粮食综合生产能力。(2)城乡居民收入不断增长过程中的消费结构升级和国内生物能源发展将会使得中国粮食需求结构发生变动,而农村劳动力跨区域流动则显著地加剧了粮食主销区域粮食供求失衡程度。(3)人民币汇率的波动在短期内有利于适度平衡国内产需缺口,但如果人民币汇率持续走低,将会使得粮食进口贸易量的增加影响到国内粮食产品的市场价格,从而不利于中国国内粮食供求的均衡格局。本文主要研究内容涉及以下六个部分:第一部分是文献综述,为本文第2章,主要是在综述有关局部均衡理论和大国贸易理论的基础上,全面、系统地总结和评述了国内外学者关于中国粮食供求均衡格局变动趋势的等相关文献研究方法及其研究结论。第二部分为本文第3章,基于中国31省区粮食生产、消费和贸易历史数据,分别探讨了中国粮食生产区域格局的变化、中国粮食消费结构的变化以及中国粮食国际贸易格局的变化趋势,同时采用空间计量经济学模型理论和方法实证研究了中国粮食供求格局变化的成因。第三部分为本文第4章,对当前中国粮食生产、消费、贸易和政策条件的变化以及中国粮食供求均衡格局面临的新形势和关键问题进行了量化分析和总结。第四部分包括第5章和第6章,本部分构建了本文的核心模型——CWARMEM,并界定了模型的研究对象范围,描述了CWARMEM模型的工作流程,建立了模型数学等式,揭示了模型各个数学方程式的经济含义;同时还详细说明了本模型以GAMS为重点软件的求解过程。随后,设计了模型数据需求结构,分别实证计量估计了生产系统和需求系统参数,并采用局部均衡模型参数校准方法将计量估计的参数调整为适合该模型运行的参数矩阵。第五部分为本文第7章。首先在第4章对当前影响中国粮食供求区域均衡变动的主要问题分析的基础上,设计了涉及粮食自然生产条件变化、粮食消费需求条件变化、粮食贸易条件变化和粮食政策条件变化四大类共9种关键情景;随后利用第5章和第6章构建的CWARMEM模型及其数据对这9种情景方案进行了模拟分析,并基于模拟结果探讨了这些情景的变动对中国粮食供求区域均衡格局的影响效应。第六部分即本文第8章,主要结论与政策建议。对全文的研究结论进行了简要总结,并基于本文的研究结论从全国和区域两个层次上提出与稳定中国粮食供求均衡、保障国内粮食安全目标相适应的相关政策建议。本文的创新之处在于:(1)首次研究了地理空间溢出效应对粮食供求区域均衡格局变动的影响效应,并运用空间计量经济学模型对其变动的原因进行了实证分析;(2)突破了以往相关研究的“小国假设”条件,考虑到了国内市场与国际市场之间所表现出的互动关系,将中国粮食供求区域均衡问题研究纳入到全球粮食市场体系下;(3)创新性地将多市场多区域局部均衡理论、大国效应理论、计量经济学方法和计算机程序化技术融为一体构建了CWARMEM模型;(4)利用CWARMEM模型实证模拟了影响当前中国粮食供求区域均衡变动趋势的9种关键情景,其中,实证量化分析农村劳动力跨区域流动和生物能源应用发展对中国粮食供求区域均衡变动的影响效应在国内尚属首次。更多还原

【Abstract】 China had been able to supply sufficient grain to feed its growing population and also supplement world grain supplies since China’s White Paper on Food Security and Grain Production was announced in 1996. However, the micro and macro environment factors that impact Chinese grain supply and demand are changing with the rapid economy development and process of Chinese rural industrialization and urbanization, even with the higher degree of Chinese agricultural marketlization and internationalization. Therefore, to investigate the effects of these factors on Chinese grain supply and demand and to examine the internal mechanism of Chinese grain supply and demand regional equilibrium is practically and theoretically significant to assure China’s food safety under the background of globalization by the effective polices and measures.Based on the literatures about Chinese grain supply and demand equilibrium, changes of grain production, consumption and international trade were analyzed firstly using the panel data of Chinese grain production in 31 provinces in China from 1978 to 2006, and then the reasons of these changes were empirically studied by spatial error model. Secondly, the current key factors effected the change of Chinese grain supply and demand were summarized and scrutinized in this dissertation. Thirdly, based on the widely used theory and structure of "Multi-market, multi-regional partial equilibrium model", the Chinese World Agricultural Regional Market Equilibrium Model (CWARMEM) that concluded 18 kinds of agricultural products and 57 regions was constructed. Further more, rice, wheat, maize, soybeans, roots and other coarse grain of Chinese 31 provinces were the primary objects studied in this dissertation. Fourthly, nine simulation scenarios were designed according the current key factors effected the change of Chinese grain supply and demand above. Then the scenarios were simulated by CWARMEM. The different results of Chinese grain production, consumption and trade under the simulations were lay out, which showed the internal mechanism about changes of Chinese grain supply and demand equilibrium. In the end, the main conclusions of this study and several policy measures were sum up. Totally, five main parts were constructed in the dissertation.The first part was about the current literature review, which is Chapter 2 in this dissertation. Based on the theory of partial equilibrium model and large country trade model, the methods and conclusions about studying the topic of Chinese grain supply and demand were reviewed. It was resulted that some limits in the most of current studies, which were especially the "small country" hypothesis not considering the commutative effects between China and the world market, and the qualitative methods which could not analyze the changes of Chinese grain supply and demand equilibrium quantitatively. So the research of this dissertation is positive to supplement the current study to some extent about this topic.The second part was Chapter 3 in this dissertation. Grounded on the panel data from 1978 to 2006, changes of Chinese provinces’ grain production, of Chinese grain consumption structure and of Chinese grain international trade were examined in the first. Then the explanations of these changes were empirically analyzed by the Spatial Empirical Economics model especially from the aspects of natural environment, technology economics, population and regional economy, and grain policy. Results suggested that the grains production in different provinces is effected by neighboring provinces in China; increasing grains production reduces grains production in the nearby provinces. Besides environment and technology progress, distinctions of average arable land area, nonagricultural employment and working income affected grains production significantly in different provinces of China; the effects were more obviously in rice and wheat production. We hypothesized that as the expanding of discrepant economy in different provinces of China; grain production would transfer and centralize to the provinces having larger arable land area, less nonagricultural employment and low salary.The third part included Chapter 4. The new development trend of the current key factors effected the change of Chinese grain supply and demand were summarized and scrutinized in Chapter 4. It was resulted that the continuous potential of Chinese grain production would be limited and the sustained demand of Chinese grain consumption would be rising, with the rural challeges from the national and international grain market environment in the coming years.The fourth part included Chapter 5 and Chapter 6, which were about the model construction, data process and parameter estimation. Firstly, based on the theory and structure of "Multi-market, multi-regional partial equilibrium model", the Chinese World Agricultural Regional Market Equilibrium Model (CWARMEM). Secondly, the scope of agricultural products and countries were established, the model working flow was created, the model 10791 mathematical equitation was formed, and the solving process of the model was showed by GAMS arithmetic. Thirdly, grounded on CWARMEM model’s structure, the data requirement and data base were built up, and then the parameters of supply and demand system were estimated and calibrated using these data.The fifth part included Chapter 7. Nine scenarios were designed, which were "Decreasing arable land resource in the process of Chinese urbanization and industrialization", "Increasing water usage for Chinese grain production", "Agricultural technology advancement for Chinese grain production", "Rigid increasing population in China", "Transference of rural labors between different provinces in China", "Changes of food consumption with increasing Chinese citizens and rural people’s income", "Appreciation of Chinese RMB", "Increasing grain industry demand in China for the development of bio-ethanol" and "Changes of Chinese grain producer subsidy policy". After then, these scenarios were simulated and different results of Chinese grain production, consumption and trade were got by CWARMEM.The sixth part was Chapter 8, which were conclusions and policy measures in this dissertation. The conclusions of whole research were summarized and the development goal and policy selection of Chinese grain supply and demand were sum up.Compared with the existing similar domestic study, the main progresses that this dissertation makes are the follows. Firstly, empirically evaluating the spatial-spillover effects using the Spatial Econometrical Models in the changes of Chinese grain supply and demand is seldom done in domestic studies. Secondly, considering the "large country effect" in the study of Chinese grain supply and demand is rarely studied in the current studies. Thirdly, on the basis of the international widely-used "Multi-market, multi-regional partial equilibrium model", the author proposes the Chinese World Agricultural Regional Market Equilibrium Model (CWARMEM), and then uses this model to simulate 9 key scenarios that are main factors effecting the changes of Chinese grain supply and demand. Lastly, since the empirical analysis is based on detailed and reasonable data process and through practical quantitative methods, the conclusions and policy implications are more scientific and of practical significance.更多还原