Effects of land use changes on grain yield and environment—A case study from Shuangcheng City,Heilongjiang Province

The land use changes of Shuangcheng City and their impacts on grain yield and environment were discussed by using the spatial analysis function of GIS on the basis of Landsat data in the years of 1986 and 2000 combined with the statistic data. The results show that the areas of cropland, meadow and water decrease annually, they were 1841.15hm², 3030.25hm² and 70.86hm² less in 2000 than those in 1986, while the areas of town, countryside, woodland and paddy increased by 581.78hm², 363.91hm², 1103.5hm² and 2934.77hm² in 2000, respectively. The grain yield presented an undulated increasing tendency, which was 373 thousand ton in 1982, and 1353 thousand ton in 2001, with the highest yield, 1651 thousand ton in 1998. The annual average temperature was rising and the mean precipitation was decreasing from 1957 to 2001.