摘要
玉米是中国大陆地区“北粮南运”的主要农产品品种，玉米区际贸易量约占玉米总产量的1／3。玉米区际贸易通过隐含在其中的“虚拟资源”流动对区域水土资源平衡产生的重要影响。玉米虚拟水和虚拟耕地资源流动量分别达到（387～500）×10^8m3和（929～1125）×10^4hm^2，两者占到玉米流出区和流入区水、土资源总量的2．6％～10％左右，说明玉米虚拟资源流动已经成为我国区域水土资源配置的重要形式。虚拟资源流动缓解了南方地区的耕地短缺，提高了全国的水土资源生产效率，却因虚拟水资源的逆向配置拉大了水土不平衡的差距。其原因主要有：①北方玉米生产的比较优势提高了平均生产效率，这种高效率通过玉米这一载体的流动传递给了南方；②水土两种资源的含义和属性差异所导致的经济重要性不同；③降水资源对北方的玉米生产具有重要贡献。玉米虚拟水土资源流动的研究结果表明，虽然耕地资源是影响我国粮食生产的最具限制性的因子，而水资源对北方地区尤其是华北地区生产发展的约束也不可忽视。缓解北方地区水资源短缺的“南水北调”工程对于改善区域水土资源平衡具有积极的意义，“北粮南运”与“南水北调”同时并存的矛盾局面也有其合理性。
Maize has played an important role in China's Mainland＇ s North-to-South grain transfer, with a volume of 47 million tons in trade, about 1/3 of the average annual maize production from 1999 - 2002. Maize exported from Northeast China to other regions of the country totaled 25 million tons, or 54.8 % of exports, and maize exported from North China to other areas totaled 21 million tons, or 45.2% of all exports. The volume of maize imported to Central China is the highest, at 14 million tons, while East China, South China, North China and Southwest China import 11, 10, 9, and 1.8 million tons respectively. Hence, maize trade makes a major contribution to China＇s regional balance of supply and demand, and has major impacts on regional water and land allocation because of the flow of ＇virtual resources＇ embodied in it. While South-to-North water diversion has been carried out in China to allocate water from the Yangtze River to the water-deficient region in northern China, grain has simultaneously been transferred from North-to-South. This paper assesses whether water transferred from South-to-North is rational, in terms of efficiency and equity, when compared to the virtual water embodied in crops traded from North-to-South. The analysis shows that maize virtual resources flow in terms of water and land allocation is equivalent to 38 - 50 billion m3 of virtual water and 93 -113 million hm^2 of virtual land, which constitutes 2.6 % ~ 10 % of total water and farmland in the maize export and import areas of China. Though the land shortage in southern China has been lessened, and productivity of both water and land resources has been increased through maize transfer, the allocation of virtual water resources is still insufficient. The causes include： 1 ） much higher productivity of water and land in the North has been transferred to the South; 2） the economic value of virtual water versus land is differently influenced; and 3） rainwater contributes to maize production in the North. These results demonstrate that although land is the biggest constraint to China＇ s grain production, water limitations in the North should also be given attention. The project of South-to-North water diversion can improve the balance of regional water and land resources, by aiming to alleviate the shortage of water resources. Therefore, the contradictory pattern of North-to-South grain transfer and South-to-North water diversion has a rational basis.
出处
《资源科学》
CSSCI
CSCD
北大核心
2008年第7期1032-1038,共7页
Resources Science
基金
中国科学院百人计划择优支持项目:“人地系统相互作用机理与空间过程”
