So, I've been genning a bunch of worlds because I wanted to build a fortress on the delta of a small river into an ocean/lake, but with easily accessible magma and other civs. Finally, I found what I wanted: Brook, ocean, lots of trees, magma pipe in the first cavern layer, temperate (frozen on embark, but will presumably thaw in summer; makes the aquifer easier to deal with)...it even had a nice little hill on the north edge of the map. I was happy. So, I embark, and I used DFreveal to see whether I really got the pipe, etc. Unfortunately, I accidentally unpause, releasing spoilers and its accompanying FPS killers (that'll learn me not to save instantly). Anyway, I went and made a copy of the region folder in the save directory, thinking that since I hadn't saved I could just re-embark on the copied world. I could even change my embark size a little to better take advantage of the site.
However, when I did so, I found the embark was completely bare of trees. Thinking maybe the changed embark size had done something, I repeated the procedure, but with the same embark size as before. Still no trees. I exported the world gen info and regenned the world. Still no trees. I've heard that DFreveal can do that to a save, but I don't understand how it could have affected the unsaved folder, much less persist over a world regen. Can DFreveal actually corrupt a world seed? Has anyone seen this before/have a clue what could have caused this/have advice how to get the trees back?