实物量与价值量加权的全球农产品贸易网络分析

用实物量与价值量对农产品贸易网络进行加权,可以揭示这种网络结构的变化特点,直观地表现各经济体之间的贸易关系。本研究用复杂网络理论构建了八大类农产品两种贸易网络,结果表明:①30年来全球农产品实物总量增加了2.55倍,增长过程平稳;价值总额增加了1.98倍,呈波动上升态势,这充分表现出全球农业经济一体化的趋势。②拟合节点强度的累积分布曲线发现,其满足幂律分布。扩展指数α随时间推移增大,表明网络中各节点的异质性增强,"枢纽"节点的功能进一步强化。③30年来,主要的贸易连线发生了大的变化,中国逐渐成为农产品的最大需求方。④两种贸易网络反映出农产品的属性差异,但主要的贸易关系逐步趋同。

Trade Network of Global Agricultural Products Weighted by Physical and Value Quantity

The agricultural product trade network weighted by physical and value quantity, which can reveal the changing characteristics of the network structure and directly response the trade relationships among countries. This paper employs complex network theory to construct two trade networks of 8 categories of agricultural products, the research results indicate that: 1) The total trade of global agricultural products based on physical quantity increases by 2.55 times in the past 30 years and shows a stable trend, the total trade value quantity increases by 1.98 times, but shows a fluctuating upward trend. The increase in total trade quantity signifies a trend of global agricultural economic integration. 2) The cumulative distribution curve of the node strength conforms to a power-law distribution. The expansion index(α)increases with time, which shows that the heterogeneity of various nodes in the network is enhanced, and the function of "hub" node is further strengthened. 3) In recent 30 years, the major trade links in the network have changed a lot, China has gradually become the largest demander of agricultural products. 4) Although there is difference of two trade network because of different attributes of agricultural products, the major trade relationships between them are gradually synchronized.