When you define multiple forest types, you must consider a constant height layer between them. For example, if you want to define 3 forest types with heights 8, 12, 20, the forest cell count should be 4, 6, 10. It means thickness of layers below the heights of the forest is 2 m.
Note that the number of forest types must be less than number of cells in Z direction. For example. If you want to define 20 types of forest, it is better to define at least 30 z-layers.
Note that when we define a forest and set vertical expansion to geometrical, first vertical cell height will be set automatically. But sometimes when we define a forest and then change vertical expansion method, this option can be set in the WindSim desktop. Remember that once we define the forest, the height of the first vertical cell cannot be set. The solution is just turn the forest off and on again.
