Tropical rain forest is described as a mosaic of ecologically uniform patches. A method is proposed to recognize and inventory the patches and to draw mosaic maps, based on the size and architecture of canopy trees. Mosaic maps from three different forest localities in Indonesia are compared in terms of the relative area occupied by each kind of patch, and the surface range and number of constituent patches. The comparison shows that the mosaic patterns are specific to the sites and can be used for the characterization of patch dynamics in different forest types. Possible implications for forest management are discussed in the light of the mosaic maps.