China's Land Carrying Capacity Based on Man-grain Relationships

With population growth and increasing pressure on land resources,land carrying capacity(LCC) and food safety have been attracting great attention worldwide.From the point of man-grain relationship and by establishing LCC and land carrying capacity index(LCCI) models,this article firstly analyzes the spatial-temporal dynamics of LCC of China from 1949 to 2005 at county,provincial and national levels.Choosing 2005 as a representative year,this article then evaluates the LCC of 264 pastoral regions(semipastoral regions),663 urban regions and 592 poverty stricken regions of the country.The results show that:(1) from 1949 to 2005,with the increase of grain production,the LCC of China has been improved conspicuously,but due to the rapid population growth,the production can only maintain a low level grain consumption;(2) over the past 25 years(1980-2005),the number of population overloading provinces decreased from 23 to 15 and the mangrain relationship has been improved gradually,but there were more overloading provinces than surplus provinces in China;(3) at county level,there were 1572 overloading counties in 1980 accounting for 68.26% of the total counties of the country and where were 649 million people lived,while in 1990,2000 and 2005,the number of overloading counties were 1066,1133 and 1087 respectively,which shows that the man-grain relationship has been improved obviously during the past 25 years;as for spatial distribution,the surplus counties were mainly concentrated in agriculture developed regions,such as Northeast Plain,North China Plain,middle and lower Reaches of the Yangtze River Plain,and overloading counties were mainly located in regions with poor natural environment and low grain production capacity,such as Northwest China,Tibetan Plateau and Loess Plateau and economically developed urban regions,such as Beijing,Tianjin and Shanghai;(4) animal husbandry improved greatly the LCC of pastoral and semi-pastoral regions,while urban regions were overloading for increasing population pressure and more than half of poverty stricken regions were overloading due to critical natural environment and poor economic conditions.