The dynamic variation analysis of cultivated land pressure in Ningxia

Cultivated land is the basic geographical resource that allows humans to exist.The pressure index of cultivated land is the ratio of minimum area of cultivated land per capita and actual area of cultivated land per capita.It is the vital indicator to measure intensity of the strains on regional cultivated land resources and its dynamic change trend.The research took Ningxia Hui Autonomous Region as sample to study cultivated land change of Ningxia from 1950 to 2007 by adopting the model of the minimum area of cultivated land per capita and the model of the pressure index of cultivated land.The resulted show that quantity of cultivated land area per capita and the minimum quantity of cultivated land area per capita were continuously decreased by 0.39hm2and 0.74hm2respectively from 1950 to 2007.By the cultivated land change,population growth,change of grain yield per unit area and policy influence,the pressure index of cultivated land showed a trend of decrease in undulation,which was positively correlated with the strict implementation of cultivated land protection policy,ecological immigration,and science and technological service by Ningxia government in recent years.