Bloom is a spell in Fall From Heaven 2 that creates a New Forest. This doesn't immediately remove resources or improvements.
Are conflicting resources or improvements removed if and when the new forest grows into a Forest or Ancient Forest?
After a couple hours of testing I can confirm BadP's comment. Neither a new forest growing into forest, nor a forest growing into ancient forest, will destroy any bonuses or improvements. (and it hurt my fps)
To test this I modified a map to have every (legal) resource and terrain combo within range of my cities. I then used workers to improve everything and had high priests of leaves cast bloom. After that I saved the game and let it run for a couple hundred turns until every square had become ancient forest. At this point there were no missing bonuses or improvements. I then loaded the saved game and ran it for a couple hundred turns again, but this time I switched to a different religion from the Fellowship because only Fellowship civs can create certain improvements on top of forests. This had no effect on the results. Again, nothing was destroyed.