In reasonably small maps (not railworld, still talking about a localized factory), I have the feeling that trees reach their maximum number way too fast. Together with the pollution, this has some very strange effects: The trees start to form ring like structures far away from your base. It looks very unnatural and not how I expected my map to look like with this mod. Maybe change the way trees spawn?

Thanks for the info, I've just started a new play-through, I'll check it out and see what can be done. In the most recent update to the mod (5 days ago), I halved the spawn rate of the original mod, might cut it down further if that's not enough.

I think the rel problem is that new trees don't grow after a certain pollution threshold. If trees are nearby, I think new trees should still spawn. Otherwise -> tree ring starts growing around the factory