中国县域人均粮食占有量的时空格局——基于户籍人口和常住人口的对比分析

依据中国第五次、第六次人口普查分区县的户籍人口、常住人口数据,借助空间自相关分析、重心曲线、空间分布图系等方法,对中国县域人均粮食占有量的时空格局及其变化强度进行对比分析。结果表明:① 中国人均粮食占有量存在明显的地域分异规律,东西分异和南北分异突出。两种人口统计口径下人均粮食占有量的全局和局部自相关特征显著,空间集聚趋势不断加强。高高集聚区向东北方向汇集,低低集聚区向东南方向汇集。② 两种人口统计口径下人均粮食占有量空间分布特征存在明显差异且有增大趋势,差别较大的县区主要集中在800 mm等降水量线以南,尤以华南区和西南区最为显著。③ 人均粮食占有量变化重心曲线呈“L”形,越向北增幅越大,越向东南减幅越大;基于分布图系、重心曲线将人均粮食占有量变化区域划分为高度增加区、中度增加区、低度增加区、基本不变区、低度减少区、中度减少区、高度减少区等7 种类型,人均粮食占有量变化格局在两种人口统计口径下存在明显差异。

The spatial-temporal patterns of per capita share of grain at the county level in China: A comparation between registered population and resident population

Per capita share of grain is a major indicator in studying the supply-and-demand equilibrium of grain. With the rapidly growing floating population in China, it is important for the decision-makers to accurately estimate the distribution of per capita share of grain and its dynamics. The variation of per capita share of grain at the finer spatial scale is ignored by most studies at national or provincial levels. Population data used in the calculation of the per capita share of grain are not consistent, but there is large difference between the size of registered population and resident population in some areas. This inconsistency will greatly influence the interpretation of the spatial pattern and trend of per capita share of grain as well as the food transportation policy. Based on the county-level data of registered population and resident population in China's fifth and sixth censuses, this paper conducts a comparative analysis of spatial-temporal patterns and trends of county-level per capita grain, when either registered or resident population is used. Several spatial data analysis methods are used, such as Global Moran's I, LISA, gravity centers curve and the thematic map series. The results show that: Firstly, per capita share of grain in China demonstrates obvious east-west and south-north divides. Per capita share of grain is significantly correlated over space no matter which population data is adopted. High-high clusters are concentrated in Northeast China, northwestern Xinjiang and parts of Central China. Low-low clusters are mainly distributed in coastal provinces in the middle and lower reaches of the Yangtze River and South China. Such a spatial agglomeration is growing over time. The spatial clusters of high values tend to form in Northeast China, while the cold spots have emerged in Southeast China. Secondly, spatial distribution of per capita share of grain differs a lot when two kinds of population data are used. Such differences grow over time, with most of them concentrated to the south of 800 mm rainfall line as well as in South China and Southwest China. This is in line with the fact that the active regions of floating population are mainly located in the eastern monsoon region to the south of 800 mm rainfall line. Although the spatial pattern of serious food shortage regions is consistent under either population standard, migration has intensified the degree of food shortage in these regions. At the same time, calculation result based on resident population shows that, more commodity grain can be exported by counties in Northeast China, Huang-Huai-Hai Region and Sichuan Province. Thirdly, the gravity center change curve of per-capita share of grain presents an "L" shape and has a greater increase and decrease to the north and southeast respectively. Integrating the thematic map series and gravity centers curve of per capita share of grain, we identify seven kinds of regions: large increase, moderate increase, small increase, zero growth, small decrease, moderate decrease and large decrease. Such patterns differ between the two population criteria.