粮价上涨对中国农村家庭微观粮食可获性的影响及其群体间影响差异研究：基于静态与动态视角

To be sufficient in food availability at the macro level is not equal to the guarantee of food access for every household. Frankly speaking, food access is more prevalent and significant in term of food security, and the capacity for rural poor households to gain enough food should be paid more attention to. Recently, as the international grain prices keeps soaring, more and more researchers believe that the food access of net buyers in China's rural households will be threaten and should be concerned. However, the reality might be slightly different from what they are worried about because of the following reasons: Firstly, the viewpoint is proposed under the assumption that all the net grains buyers and sellers are homogeneous when they confront with prices increasing. But actually the households are heterogeneous and the impact of gains prices' rising on households with different characteristics will be different, which need to be further examined; Secondly, the conclusion was drawn from the static perspective only. But as prices keeps increasing, rural households will adjust their behaviors of grains production and consumption, and the dynamic analysis will be more accurate and meaningful. As a result, the adjustment of both the assumption and analysis perspectives should be emphasized and reflected in the framework of food access of rural households in China. And this project divide the rural households into different groups by their ability to resist the shocks, and then empirically examine the impact of rise in grains prices on the food access of rural households and different groups by both static and dynamic perspectives. This study is not only favorable for enrich the former food security framework, also beneficial for China to response to the increasing grains prices in order to safeguard the food security.

粮食总量供给充足并不能确保微观个体的粮食可获性。就保障粮食安全而言，微观个体的粮食安全值得广泛重视，而相对更为贫困的农村家庭的粮食可获性理应获得更多关注。近年来国际粮价持续上涨使人们对多为粮食净买者的中国农村家庭的粮食可获性产生担忧。然而该观点基于粮食净买者与净卖者维度的群体划分方式所暗含"同质性"假设的不切实际、强调总体影响的同时对"群体间影响差异"这一评价标准的忽视、以及局限于静态分析的单一视角，很可能导致判断的偏差。对以上三方面进行积极修正，并将其纳入粮价上涨对农村家庭粮食可获性影响的分析框架，对该影响的合理判断具有重要意义。本研究以"抗冲击能力差异"维度划分农村家庭群体，基于静态与动态两个层面多种影响作用机制，分析并测度粮价上涨对农村家庭粮食可获性的总体影响及其在不同群体间影响的差异，丰富和完善本领域研究视角和分析框架的同时，也为中国应对粮价持续上涨、保障微观粮食安全提供研究参考。

基于微观粮食安全视角，粮价上涨对农户粮食可获性的影响是需要多方面综合考量的问题。直接比较粮食净买者与净卖者数量来作出判断存在三点逻辑缺失，即农户间“同质性”假设的不切实际，忽略群体间影响差异，以及单一的静态视角，很可能导致判断偏误。本研究以抗冲击能力维度划分群体，基于静态与动态层面多种影响机制探讨粮价上涨对农户粮食可获性的总体影响及群体间影响差异。研究从静态层面展开，分析粮食净买者与净卖者群体特征差异并讨论其在受冲击程度和抗冲击能力上的差异。研究结果表明，总体上，粮价上涨使农户因获得来自相对富裕的城镇家庭的利益转移而实现总体利益提升；群体细分上，净卖者因粮价上涨而直接获益，而受损的净买者抗冲击能力却优于前者，粮价上涨引发农村内部由高收入向低收入群体的利益转移。随后研究进入动态层面，探讨间接效应、溢出效应和乘数效应的作用机制。在间接效应方面，研究测算各群体粮食需求与供给弹性，考察粮价上涨时各群体生产消费决策的调整及群体间差异。研究结果表明，总体上，粮价上涨时农户的生产消费决策调整令其福利高于静态初始水平；群体细分上，强势群体决策调整面临更高的机会成本，对粮价较不敏感，在粮价上涨中获益少于弱势群体。在溢出效应方面，研究在理论验证基础上实证分析粮价上涨对粮食与非粮食投资、生产和收入的影响，研究结果表明，总体上，粮价上涨引发农户生产可能性边界外移以及生产的收入效应和替代效应，新生产点落在更高的等收益线上；群体细分上，弱势群体生产边界外移更大且呈现更强的边际生产倾向，生产的收入、替代效应均更显著，在粮价上涨中获益更多。在乘数效应方面，研究测算群体间粮食与非粮食生产消费互补性差异以及各群体分别对粮食及非粮食边际消费倾向差异，据此测算粮价上涨对各群体影响的乘数。研究结果表明，总体上，粮价上涨时群体间生产、消费及收入呈现不断收敛、相互加强的连锁反应，新均衡收入高于静态初始水平；群体细分上，群体间粮食生产消费互补性强于非粮食，而净买者粮食边际消费倾向高于净卖者非粮食边际消费倾向。两者在乘数效应中分别拥有初始和后发优势，而后者比前者拥有更大乘数，在粮价上涨中获益更多。此外研究还延伸到关联领域，如对传统粮食安全观的重新审视，粮价变化下粮食生产可持续性及种植结构变动问题，生产消费决策调整下的就业变化及潜力问题，粮食进口及消费趋势问题等，并已得出相应结论，为本课题研究提供了支持和逻辑延展。