Unlike Unreal Engine 2, terrain is light mapped now. However, if the quality of the light map is not satisfactory enough, it is possible to bump up its quality. To do so, open up the properties of the terrain and expand the Lighting section. Enable bIsOverridingLightResolution, and enter a higher value under StaticLightingResolution.
We have assigned a light map to the terrain so when static meshes are introduced to our map and light hits the meshes, we will get dynamic shadowing, giving a more atmospheric approach to our map.
Foliage layers are embedded into regular terrain material layers, and are thus linked to the material. Paint another material over the one that contains the foliage layer, and the foliage layer too will disappear.
In the generic browser, browse to the terrain material of the layer of choice, usually found within the Mylevel...