近20年中国粮食生产变化特征及其对区域粮食供需格局的影响

中国是一个农业大国,用占世界不到9%的耕地养活了占世界近20%的人口。国家及区域尺度粮食安全问题一直备受关注。以省为研究单元,借助GIS空间分析与统计工具,分析了1999—2018年中国粮食生产变化的总体特征、地域格局演变特征及这些变化对区域粮食供需格局的影响。研究结果表明：全国粮食总产量呈现显著增加的趋势,增长率为0.11亿t/年。北方粮食总产量呈显著增长趋势,而南方粮食总产量基本维持稳定。玉米产量的增加对这些变化起到了主导作用。在省域尺度上,近20年五种主要粮食作物（稻谷、小麦、玉米、豆类和薯类）产量时空变化具有较大差异。粮食产量的变化对区域粮食供需格局产生了较大影响。特别是东南沿海地区的广东、浙江、福建三省,从稻谷和小麦两大口粮供过于求型变为了供给不足型省份。但在全国尺度上,人均粮食占有量在Y 1999—2003时段（1999—2003年五年平均情况）和Y 2014—2018时段（2014—2018年五年平均情况）分别为368.0 kg/人和461.5 kg/人;人均两大口粮占有量在Y 1999—2003时段和Y 2014—2018时段分别为220.3 kg/人和247.6 kg/人。播种面积的变化是全国及区域尺度上粮食作物产量变化的直接原因。但其根本原因则更多归因于土地利用价值驱动的属性、功能及质量的变化。此外,根据导致耕地减少的四种主要类型——“非农化”“非粮化”“荒废化”和“生态化”,探讨了其形成原因并提出相应的提高区域粮食生产的对策建议,以期对区域粮食种植格局调整及实现两大口粮需求省份向自给型省份转型提供参考。

Change in grain production in China and its impacts on spatial supply and demand distributions in recent two decades

China is feeding roughly 20% of the world's population with less than 9% of the world's cultivated land. The food security at national and regional scales has been a major concern. In this study, we took the province-level area as the research unit and utilized GIS spatial analysis and statistical tools to examine the overall characteristics of grain production changes, the evolution characteristics of regional patterns and the impact of these changes on regional grain supply and demand pattern in China during 1999-2018. The results showed that the total national grain output significantly increased with an annual rate of 1.1 million tons. The total grain output of Northern China showed a significant growth trend, while that of Southern China remained stable. The increment of maize yield played a leading role in these changes. The spatio-temporal yield variations of five major food crops (rice, wheat, maize, beans and tubers) were quite different in the past 20 years at provincial-level scale. The change of grain yield had great influence on regional grain supply and demand pattern. Particularly, Guangdong, Zhejiang and Fujian provinces located in the southeast coastal region had changed from supply-oriented provinces of major grains with rice and wheat into demand-oriented provinces. However, the per capita share of grain was 368.0 kg/person in Y 1999-2003 period(the five-year average during 1999-2003) and 461.5 kg/person in Y 2014-2018 period (the five-year average during 2014-2018) at national-level scale, respectively; and the per capita share of the two major grains was 220.3 kg/person and 247.6 kg/person in Y 1999-2003 and Y 2014-2018 periods, respectively. The change of sown area was the direct reason for the change of grain crop yield at national and regional scales. Nevertheless, the fundamental reason was more attributed to the change of attribution, function and quality, which is driven by land use value. Our study classified the reasons for the decrement of cultivated land into "non-agriculture" "non-grain" "wastage" and "ecology" types. Considering the formation causes of each type, the corresponding countermeasures and suggestions for the sustainable use of regional cultivated land were put forward in order to provide reference for the adjustment of regional grain planting pattern and the transformation of demand-oriented provinces of two major types of grain to self-sufficient provinces.