多层农产品贸易依赖网络供应风险传播研究——以玉米和猪肉为例

Research on Supply Risk Propagation in Multi-Layer Agricultural Product Trade Dependency Networks—A Case Study of Corn and Pork

摘要: 全球化农产品贸易是维系各国农产品安全与优化资源配置的重要途径，但其高度互联的贸易网络也隐含着系统性连锁灾害风险。尽管学者们针对农产品贸易网络的脆弱性及风险传播展开了广泛探讨，但主要聚焦于单一农产品贸易网络的分析，忽视了不同农产品之间的依赖关系，导致对系统性风险的低估。为此，本文以玉米和猪肉两种典型的上下游关联农产品为例，构建相应的贸易依赖网络，在对其分析的基础上，建立基于负载–容量的级联失效模型，模拟并分析了玉米供应短缺情境下双层贸易依赖网络上的风险传播。研究结果表明：(1) 不同风险水平下，各国的风险波及规模存在显著异质性，整体呈阶梯式下降趋势，反映出各国影响力水平的差异；同时，随着层间依赖程度增大，风险逐渐向下游猪肉贸易网络扩散，跨层传播效应显著增强。(2) 风险传播模式存在主体差异性，核心玉米出口国发生供应危机时，会率先在玉米贸易层内引发大规模风险扩散，进而迅速传导至猪肉贸易网络；而少数非核心玉米出口国，其初始玉米层内风险波及规模虽较小，但能够通过中介国家的放大作用，最终同样诱发显著的跨层传播。本文为理解多层农产品贸易依赖网络上的风险传播提供了理论依据，同时对构建更具韧性的农产品贸易体系具有重要的现实意义。

Abstract: Global agricultural trade serves as a vital channel for maintaining national food security and optimizing resource allocation. However, its highly interconnected trade network also harbors the potential for systemic cascade risks. While scholars have extensively explored the vulnerability and risk propagation within agricultural trade networks, existing research primarily focuses on single-product trade networks, overlooking the critical dependencies between different agricultural products. This oversight leads to an underestimation of systemic risks. To address this gap, this paper takes corn and pork—two representative products with an upstream-downstream relationship—as examples, based on network analysis, a load-capacity-based cascade failure model is established to simulate and analyze risk propagation across the two-layer trade dependency network under a corn supply shortage scenario. The findings reveal that: (1) Under different risk levels, the scale of risk impact exhibits significant heterogeneity among countries, showing an overall stepwise decline, which reflects variations in national influence. Simultaneously, as the degree of inter-layer dependency increases, risks gradually diffuse to the downstream pork trade network, with cross-layer propagation effects becoming markedly stronger. (2) Risk propagation patterns demonstrate source dependency. When core corn exporters face a supply crisis, they initially trigger large-scale risk diffusion within the corn trade layer, which then rapidly transmits to the pork network. In contrast, for a few non-core corn exporters, while the initial propagation within the corn layer is limited, it can ultimately induce significant cross-layer propagation through the amplification effect of intermediary countries. This research provides a theoretical basis for understanding risk propagation in multi-layer agricultural trade networks and holds practical significance for building a more resilient global agricultural trade system.