Spatiotemporal Variation and Driving Forces on Cultivated Land Change in Transitional Area between Pastoral and Agricutural——A Case of Cultivated Land Change of Ulanqab

According to the land use change data by remote sensing images from 1990 to 2010,this paper studied the quantitative dynamic changes of cultivated land in Ulanqab City in the farming-pastoral zone of north China.Some mathematic models were used to study the spatiotemporal change of cultivated land from 1990 to 2010in Ulanqab City,such as land use dynamic degree model,land use type transferring matrix model,and discussed its driving factors.The results indicate that the change of cultivated land in Ulanqab City from1990 to 2010,was mainly the cultivated land and grass land changes alternately;the increase of cultivated land from 1990 to 2000,was mainly from grassland,and the cultivated land was decreased in 2000—2010,which was changed into grassland and woodland;during years of 1995—2005,cultivated land change was most significant and the average dynamic degree of land use was 0.55%;population growth,nature conditions,policies and the implementation of ecological engineering were the major driving factors.