Well, if you read this thread a bit you might notice that the idea to have a building evolve into a forest instead of simply have workers directly plant it was introduced to balance this out. What else would you suggest?
About the AI ... the AI will never build the Tree Nursery, because it doesn't add any bonuses to a tile. In fact, reforestation doesn't really do you that much good, and with the 25 turn delay in place before you could go ahead and chop the forest down, I don't think it does much good, either. It's more of an aesthetical thing, except the health bonus it will give you once you get enviromentalism.
_____
rezaf
About the AI ... the AI will never build the Tree Nursery, because it doesn't add any bonuses to a tile. In fact, reforestation doesn't really do you that much good, and with the 25 turn delay in place before you could go ahead and chop the forest down, I don't think it does much good, either. It's more of an aesthetical thing, except the health bonus it will give you once you get enviromentalism.
_____
rezaf