Analysis the Dynamic Changes of Cultivated Land in Chongqing City and Their Driving Forces

According to statistical and survey data from 1996 to 2005,quantitative dynamic changes of cultivated land in Chongqing City during the last 10 years are discussed.By using the principal component analysis,the mechanism of driving forces for these changes are analyzed.The result indicates a general decreasing trend of the area of cultivated land during the past 10 years and an increasing rate of conversion cultivated land to other land uses since 2001.The driving forces of cultivated land change are mainly economic development,re-adjustment of agricultural production structure,population growth,the present policy of returning farmland to forests.