The study selected MODIS land use data and analyzed the spatial and temporal characteristics of forest and grassland after the implementation of the Grain to Green Program, as well as the impact of policy changes on the changes of forest and grassland. The following results are obtained. 1) After the program’s implementation, the overall trend of forest land and “cropland land broadly defined” including orchards in China showed a small upward trend, and the trend of grassland showed a downward trend. 2) Considering that part of the orchards and forest land have not destroyed the arable layer, which can be effectively restored to cropland, there is no tendency to lose the cropland, and the red line of 1.8 billion mu (1.2 million km²) of cropland is not currently under threat. 3) Returning cropland to forest mainly occurs in Yunnan Province, Sichuan Province, and Heilongjiang Province, accounting for 9.72%, 9.28%, and 7.68% respectively of the total area of cropland converted to forestland (109500 km²) nationwide. In contrast, the conversion of forestland to cropland mainly occurs in Sichuan, Hunan, and Guizhou Provinces, accounting for 18.47%, 9.59%, and 9.35% respectively of the area of forestland converted to cropland (104400 km²) nationwide. The simultaneous existence of a large number of both croplands converted to forest and forest converted to cropland in Sichuan and other provinces may be due to benign adjustments in geographic location and land quality, or it may be due to the regional heterogeneity of the policies of “food security” and “environmental protection”, which need to be further studied. 4) Half of the “forest land” after returning cropland to forests has been cultivated again after 18 years, some of it has been preserved as forest land (37%), and a tiny part of it has been degraded to grassland (3%) (taking the forest land cultivated in 2001 and returned to forests in 2002 as an example). 5) Subsidies for the Grain to Green Program can reduce the proportion of “forest land” converted from cropland for replanting crops, but increase the conversion of land from cropland to forest land where the natural conditions are unsuitable for afforestation. 

grain for green program, land-use change, spatial and temporal characteristics, subsidies, replanting; degradation, conservation