I recently cleared an area of black forest, and I kinda wish it would turn into Meadows, if I planted enough birch trees, or plains, if I didn't do anything. Maybe it could turn into ash or mist lands too.
I also kinda wish that old abandoned bases could end up being haunted with ghosts, or you might find some draugr, or skeletons in there. Maybe if the enough of the structure becomes weathered and the sources of light stay unlit for a long time, then things start to happen.
Maybe you could make your plains base safer by putting up a lot of black forest trees to attract gray dwarves. Maybe the pseudo plains would only attract mosquitoes, at first, and then if you just destroy the land, it might start attracting fulings. Also, meadows wouldn't turn into anything. Maybe you could make swamp more hospitable too.
Anyway, just the thought of having to take care of the land a little bit is a fun thought to think about.