Spatial and Temporal Variation Characteristics of Desertification in Songnen Plain in the Past 50 Years

With the remote sensing image of 1975，2000 and 2018 as data source，the Songnen Plain nearly 50 years of spatial and temporal variation characteristics of land desertification and evolution were analyzed，using the man-machine interactive visual interpretation method to extract desertification information，combining with geographic information system（GIS）spatial analysis technology，dynamic calculation，transfer matrix analysis and landscape pattern analysis.Results showed that from 1975 to 2000，the total area of desertification land in Songnen Plain illustrated an obvious development trend，while the total area increased by 7 061.60 km2，and it was mainly distributed in the southeast of Songnen Plain；from 2000 to 2018，the total area of desertification in Songnen Plain decreased by 10 387.46 km2，and the desertification trend has been improved.