1985-2015年黄土高原地区粮食生产空间格局变化及原因

针对黄土高原地区扩大退耕还林还草是否会引起区域粮食供给不足的问题，利用1985—2015年黄土高原地区县级单元人口、粮食产量、播种面积、单产等数据，采用分级法和空间自相关分析法研究黄土高原地区粮食生产时空分异特征，运用对数平均迪式分解法探讨不同时期粮食单产与播种面积对粮食增产的贡献率。结果表明:2015年黄土高原地区粮食总产量和人均粮食产量分别达4.45×10⁷ t和396.53 kg，分别为1985年的1.97，1.39倍；粮食生产空间分布不平衡，284个县级单元之间粮食产量相差较大，1985—2015年粮食生产空间格局呈现逐渐由南向北、由东向西的转移趋势；粮食生产主要依靠单产支撑，1985—2015年粮食增产2.19×10⁷ t，其中单产贡献率达94.25%，面积贡献率仅5.75%，但近几年单产贡献率下降应引起重视。该研究有助于提高对黄土高原地区粮食生产的认识，为区域制定粮食生产政策和生态退耕政策提供一些参考依据。

Spatial Pattern and Changes of Grain Production in Loess Plateau Region Between 1985 and 2015

The problems of soil erosion, deterioration of ecological environment, backward economic development and grain shortages have long plagued the Loess Plateau region, which has attracted widely concerns of both government and academic circles. The Grain for Green Project implemented in the period 1999-2003 was the largest active revegetation programme in China, and the Chinese government has formulated a series of policies to expand the Grain for Green initiative. One concern with further expansion of Grain for Green is the availability of farmland and hence local food supply. In this paper, we firstly used the data of population, grain output, sown area and yield per unit area, and utilized the classification method and spatial autocorrelation analysis method to study the changes of the spatial distribution of grain production in Loess Plateau region between 1985 and 2015. Then, on this basis, we analyzed the factors contributing to the grain output increases by applying logarithmic mean weigh division index method. The analytical results showed that:(1) the capacity of grain production in Loess Plateau region had greatly improved, the total grain output and per capita grain output reached 4.45×10⁷ t and 396.53 kg in 2015, respectively. The local food production had already exceeded the satisfaction level food security, which laid a solid material foundation for further expansion of Grain for Green; (2) the spatial distribution of grain output in Loess Plateau region was uneven among the 284 counties, it also showed a trend that the spatial distribution of grain production was shifting from south to north and from east to west gradually; (3) the grain production in Loess Plateau region was mainly relied on the improvement of yield per unit area in the past 30 years; the regional grain output increased by 2.19×10⁷ t from 1985 to 2015; the contribution of yield per unit area accounted for 94.25%, which was much more than the contribution of sown area which just accounted for 5.75%; (4) we argued that continued expansion of revegetation in eastern mountainous area and loess hilly area would not cause food deficit. We suggest that the grain sown area in Erdos windy-sandy area should be reduced to save water resources; (5) this study could help increase the acknowledge of the grain security and ecological problems in Loess Plateau region from a historical and overall perspective, and also provide some references for the government to formulate policies to balance the regional grain production and ecological environment.