Change of cropland in typical area of Middle-Lower Yangtze Plain over the past 30 years

Abstract

In order to analyze the spatial- temporal change characteristics of the cropland in typical areas of Middle-Lower Yangtze Plains from 1984 to 2010,the authors extracted the land cover information of the study area in1984,1990,1995,2000,2005 and 2010 from Landsat TM /ETM+images. The results show that the amount of cropland decreased over the past 30 years. There were three stages of the cropland change: Fast reduction,slow reduction,and sharp reduction. The total area of cropland loss was 374. 10 km2from 1984 to 1990. The decrease of cropland was 66. 09 km2from 1990 to 2000,and the loss speed was relatively slow. The cropland in the study area was reduced rapidly to 1 724. 33 km2from 2000 to 2010. Most of the lost cropland was transformed into the construction land,and the cropland in cities along the Yangtze River,such as Nanjing,Maanshan,and Wuhu,was decreased more seriously than that in counties. The speed of urbanization was accelerated. Moreover,plenty of cropland was turned into ponds to breed fish and crabs around the Shijiu Lake and the Gucheng Lake,particularly in western regions where the conversion was prominently frequent from 1990. On the other hand,cropland was increased along the boundary of cropland and mountain from 1984 to 2000. After that,the cropland decreased because of the implementation of returning cropland to forest and creating economic forest.