Growing Procedural Foilage only on landscape

I am really liking the Procedural Foilage Spawner for quickly populating large areas with vegetation. To control which areas doesn’t get foliage I’m using landscape layers as described in the documentation, but I haven’t figured out how to ignore non landscape geometry. How would I use it to grow trees on a large landscape, without having trees grow on other geometry, like a lake or buildings?

Thanks,