Analysis On The Spatio-temporal Changes Of The Cultivated Land-Grain-Population System In China In The Past 10 Years

In recent years,with the rapid development of the economy and the continuous improvement of the urbanization,the cultivated land resources in China are decreasing.So,the grain consumption and demand will be increasing as a result of continuous population growth.Meanwhile,there are some differences in the spatial distribution among cultivated land resources,grain production and population.Therefore,the study of the spatial and temporal change characteristics and their coupling relationships of the cultivated land—grain yield—population system will be crutial,and it will have some useful theoretical and practical reference value for ensuring Chinese food security and rationally formulating population and agricultural policies.The research is based on the fundamental data of Chinese cultivated land area,grain yield,and population in 2009-2018.By using the center of gravity model,the cultivated land pressure index model and so,the research has concluded the spatial and temporal variation and the coupling relationship of the cultivated land—grain yield—population system of China in the past 10 years and analyzed the characteristics of the spatial and temporal variation of cultivated land pressure index which reflects the overall change of the system.The main conclusions are as follows:(1)During the study period,the cultivated land area in China shows a decreasing trend,while the grain yield and population both show an increasing trend.From the spatial change perspective,the cultivated land area shows a "increasing in the west and decreasing in the east" state,the grain yield shows a "increasing in the north and decreasing in the south" state,and the population shows a "increasing in all regions of China apart from the northeast region " state.(2)There are some differences in the spatial distribution of cultivated land resources,grain yield and population in China.It mainly manifests as follows: the cultivated land with higher grain yield mainly distributes in several eastern provinces,but the amount is small.Most cultivated land with lower grain yield distributes in the central and western regions.It causes the significant spatial differences in grain yield.The proportion of grain yield in the north of China is much higher than that in the south,but the population in the south is larger than that in the north.It results a huge spatial inconsistency between Chinese grain production and consumption.(3)During the study period,the center of gravity of cultivated land,grain yield and population in China generally moved in different directions.The cultivated land center of gravity moved from west to north,the grain yield center of gravity moved from north to east,the population center of gravity moved in the direction of northeast and southwest.The different moving directions of the three centers of gravity reflect the inconsistencies in the regional fluctuations of cultivated land,grain yield and population in China,which will further increase the differences in the spatial distribution among the cultivated land,grain yield and population in China.(4)The relationship among the annual average distance of the center of gravity of cultivated land,grain yield and population is grain yield> population> cultivated land,which shows that the number of the three also has such a relationship same as the regional fluctuations.In terms of the distance among the three centers of gravity,the distance between the center of gravity of cultivated land and grain yield is relatively small and tends to decrease,which reflects the fundamental role of cultivated land resources for grain yield.(5)During the study period,the cultivated land pressure in most areas of China shows a decreasing trend.However,there is a state of "polarization": the provinces with large cultivated land pressure shows an increasing trend,while the provinces with small cultivated land pressure shows a decreasing trend.From the spatial distribution perspective,the cultivated land pressure in each province generally shows a situation of "lower in the north and higher in the south" and "lower in the east and west,and higher in the middle.