世界农业

本文基于2006—2021年“一带一路”共建国家间的谷物贸易数据构建贸易网络，使用社会网络分析法从整体、社群和个体多层次分析贸易网络的拓扑结构及演变特征，并采用时态指数随机图模型(TERGM)对影响谷物贸易网络形成的内外部机制进行动态分析。研究发现：(1)从整体性看，贸易网络具有较高的平均聚类系数和较短的平均路径长度，存在区域集聚现象；贸易网络具有脆弱性与不稳定性，易受外界不确定性因素影响。(2)从社群角度看，贸易网络的社群数量呈现下降趋势，网络整体性得以提升；地理因素是影响贸易社群网络形成的关键成因，各国倾向于与邻国建立贸易链接；各国基于农业资源禀赋差异形成了农业资源较强的东南亚、南亚、东欧等谷物出口主导的社团以及农业资源较弱的中东、北非的谷物进口社团。(3)从个体角度看，印度、乌克兰、俄罗斯与泰国等国家在贸易网络中具有较强的贸易优势且扮演着贸易核心国的角色；罗马尼亚、保加利亚、土耳其、阿拉伯联合酋长国和巴基斯坦等国家在贸易网络中担任“中间人”角色并对其他国家的贸易关系的选择产生间接影响；中国在贸易网络中是重要的谷物进口大国，具备较强影响力。(4)谷物贸易网络既受互惠效应、集聚效应、多连通性、联通闭合效应与时间依赖效应等内生机制影响，亦受贸易国的人均GDP、人均耕地面积、人口规模、地理空间网络和法律渊源网络等外生机制变量的影响。

Based on the cereal trade data between countries participating in“the Belt and Road”from 2006 to 2021,a trade network is constructed.Using social network analysis, the topological structure and evolution characteristics of the trade network are analyzed from multiple levels of the whole, community, and individual.The Temporal Exponential Random Graph Model(TERGM) is adopted to dynamically analyze the internal and external mechanisms that influence the formation of the cereal trade network.The study found that:(1)From an overall perspective, the trade network has a high average clustering coefficient and a short average path length, indicating the phenomenon of a“small world”.The trade network is fragile and unstable, easily influenced by external uncertainties.(2)From a community perspective, the number of communities in the trade network is declining, and the overall integrity of the network is improving.Geographical factors are the key drivers for the formation of trade community networks, and countries tend to establish trade links with neighboring countries.Based on differences in agricultural resource endowments, countries have formed cereal export-oriented communities in Southeast Asia, South Asia, and Eastern Europe, as well as cereal import communities in the Middle East and North Africa with weaker agricultural resources.(3)From an individual perspective, countries such as India, Ukraine, Russia, and Thailand have strong trade advantages in the trade network and play the role of trade core countries.Countries like Romania, Bulgaria, Turkey, the United Arab Emirates, and Pakistan play the role of“brokers”in the trade network and have an indirect impact on the choice of trade relations of other countries.China is an important cereal importer in the trade network and has strong influence.(4)The cereal trade network is influenced by endogenous mechanisms such as reciprocity, clustering, multi-connectivity, closure, and time-dependence, as well as exogenous mechanisms variables such as per capita GDP,per capita arable land area, population, territorial contiguity network, and legal network of trading countries.