Characteristics of grain production and spatial pattern of land carrying capacity of China

China has made great achievements in grain production during the recent 60 years. However, still considered one of the largest developing countries with a fast population growth in the world, China’s food security has always been a global concern and an important topic in the world, in which land carry capacity based on grain and population is one of the important fields. In this study the characteristics of China’s grain production was analyzed and summarized firstly, and then, land carrying capacity (LCC) and land carrying capacity index (LCCI) models were developed from the point of man-grain relationship. Finally, the LCCI was calculated for each county of China in 2007 and systematically evaluated towards the land carrying capacity and its spatial pattern. The results showed that: from 1949 to 2008, with a periodic fluctuation, the grain production of China showed an upward tendency from 200 million to 500 million tons. The population growth rate (an increase of 145%) was less than that of grain yield (an increase of 367%), and the grain yield per capita rose steadily from 209 kg in 1949 to 400 kg in the early 21st century; food deficits and population overloading remained the primary characteristics of China's LCC at a county scale in 2007. The grain surplus counties located in the major grain-producing areas so that the population was less than the regional LCC, such as Northeast Plain, North China Plain, the middle reaches of the Yangtze River, Hexi Corridor, Hetao Plain and Sichuan Basin. While, those counties located in southeast coastal regions of China with a high population density, and regions with critical natural environment and low grain production, such as the arid region of Northwest China, the Tibetan Plateau, the Loess Plateau, the Yunnan-Guizhou Plateau and the Mountain of North China, had a man-grain conflict and appeared to be population overloading. China had a large net grain surplus at a national scale in 2007, thus for counties with a deficit in grain production, large amount of grain should be traded and transported from other China’s regions in order to meet people’s demands. It should be remarked that city-clustered regions located in eastern and central part of China, such as Beijing, Tianjin and Hebei region, the Yangtze River Delta, the Pearl River Delta and Wuhan Metropolitan Area and so on, had a tenser man-grain conflict than others. Along with the rapid development and urbanization trends in China, the man-grain conflict in these regions will become more and more severe, and the trade and transportation of grain will also appeared to be even more important.