Dynamics and trends in cultivated land in lower Yangtze Valley in the past decade
近10年来长江下游地区耕地动态变化特征

Based on the multi-temporal remotely sensed data of TM,this research attempted to reveal the spatio-temporal trends in cultivated land in the lower Yangtze Valley by depicting and analyzing the intensity of cultivated land loss and transformation modes related to the cultivated landuse,the environmental impacts associated with cultivated landuse transformation were also discussed.The results showed that:1)The transformation between cultivated land and woodland,shrubs&water body acted as the main contributors to the changes in cultivated land,leading to remarkable reduction both in quantity and quality of the cultivated land in the lower Yangtze Valley from1988to1998,2)The transformation from cultivated land to the urban landuse reflected the rapid encroachment to farmland in the process of urbanization.This process is most obvious in the major urban areas of the Yangtze River Delta such as Shanghai,Suzhou-Wuxi-Changzhou District,Nanjing and Hangzhou,where urbanization is believed to be most intense nation wide in the past decade,3)The rate of cultivated land loss is0.77%,which mainly occurred in the Yangtze River Delta and Caohu Lake Basin where is dominated by the large area of high quality cultivated land well equipped with irrigation system.On the other hand,the newly developed cultivated land was observed mainly in coastal region and hilly area.In general,the resource dynamics of cultivated land in the lower Yangtze Valley in the past decade was dominated by the drastic decrease in quantity and the obvious decline in quality.A series of ecological problems were also highlighted in the process of landuse transformation related to the cultivated land.