TreeMig model, a spatially explicit and linked forest landscape model originally based on a forest gap model, which takes additionally into account tree species migration. In each cell (sidelength from 25m to 1km) of a rectangular grid, forest dynamics is simulated at the species level, including environment dependent reproduction, growth, competition, and mortality, and between-cell seed dispersal which allows the simulation of migration. Within-cell vertical and horizontal structure is depicted by frequency distributions of tree density in height classes and therefore light attenuation.