What is the name of the movie with little elves in a forest that gets destroyed by a black oil monster?

The answer is Fern Gully and the forest doesn't get cut down and there was a sequel Fern Gully 2: The Magical Rescue. i have been trying to figure it out for years...i really don't know. does the forest get cut down by machines and the oil monster is at the machines? Ferngully.