Hi,
I really like the mod, but I don't think the trees should grow in concrete.
I have a large base and there have been times where I come back to an area and it has filled in much of the area with trees. This is a real problem to clear - especially in the refinery area where accidentally deleting one pipe stops everything.
I can understand gravel, stone, or even brick. I would love to get creative and leave a section of a factory floor with grass, then have the trees re-grow within that grass area.
thanks,
jon