SPS措施对农产品贸易的影响——基于Heckman两阶段方法的实证分析

SPS措施是WTO框架下农产品贸易的主要非关税措施。进口国设立SPS作为一种产品质量门槛，其遵从成本首先影响企业的市场进入行为，进而影响其贸易流量。发达国家的出口企业在资金、人才、技术和供应链系统方面更具有遵从的优势，贸易可能由发展中国家转向发达国家。对SPS措施贸易偏转效应的实证检验发现，在SPS措施实施的第一和第二年，贸易偏转效应不明显，原因在于SPS协议对发展中国家有区别对待原则，且农产品生产的区域特征明显。但在SPS措施实施的第三和第四年，农产品进口来源由发展中国家转向发达国家，存在贸易偏转效应。作为农产品出口国，这要求中国的出口企业提高技术水平，增加农产品产业链的固定投资，以遵从国外SPS措施为契机，提高农产品质量层次。

Effects of SPS Measures on Agricultural Products Trade: An Empirical Analysis Based on Heckman's Two-step Method

Sanitary and phytosanitary （SPS） measures are the main non-tariff measures for the trade of agricultural products under the framework of WTO. The importing countries set SPS measures， based on the consideration of preventing risks， protecting consumers， and protecting plants and ecological environment from being damaged by the exotic pathogens， biology and insect pest carried by agricultural products. However， SPS measures can easily be overused as trade barriers restricting foreign products. Therefore， the impact of SPS measures on the export of agricultural products has been the focus of scholars' research， but there has been scant research on the impact of the same SPS measures on the country of different levels of development. In fact， as a product quality threshold， the compliance cost of SPS first affects an enterprise's market entry behavior， followed by the impact of trade flow， i.e. SPS measures affect the binary boundary， the breadth and the depth of agricultural products. Confronting the SPS measures of importing countries， especially developed countries， the export enterprises of developed countries have more compliance advantages than those of developing countries in terms of capital， talent， technology and supply chain system. Trade may divert from developing countries to developed countries. The trade diversion effect in theory has not been verified in empirical analysis yet. Based on the firm heterogeneity assumptions of new-new trade theory， this paper analyzes the difference impact of SPS measures on heterogeneous firms， and then empirically test the trade diversion effect of SPS measures by adopting China's import trade data of agricultural products （HS01-24） between 1995 and 2013， and the data from such developed countries as EU， Australia， Japan， the United States， and Canada， and by employing the Heckman's two-step method. It has found out that in the first and second years when SPS measures are implemented， trade diversion effect is ambiguous because of the principles of differential treatment for developing countries in SPS agreement， and the resource endowment of agricultural production. However， in the third and fourth years of implementation， the import source of agricultural products from developing countries switches to developed countries. Based on the weaknesses of developing countries in the SPS measures， international organizations such as the standard and trade development facilities have been helping the traditional industries in developing countries since 2004 to adapt to the SPS measures of developed countries. The trade diversion effect of SPS measures will be beneficial to China， the world's largest importer of agricultural products， who can increase import quality and safety level of agricultural products by implementing SPS measures. But this will challenge China as an exporter of agricultural products as it requires China's export enterprises to take the opportunity of complying with the foreign SPS measures to improve product quality by upgrading their technological level and increasing the fixed investment in the industrial chain of agricultural products．