Released in 1993, with its strong environmental message, it's impossible not to compare 'Once Upon a Forest' with 'FernGully', and for my money it comes out well ahead. Whereas FernGully came across as rather half-hearted and at times a little irritating, this overlooked movie is a much more cohesive, emotionally satisfying affair, which really doesn't have any weaknesses. There are some respects in which I suppose it could have been better, but it's hard to point to anything to really criticise.
Three young 'furlings' (Abigail the mouse, Russell the hedgehog and Edgar the mole) have to go on a perilous journey to find healing herbs to save their young badger friend Michelle who has been exposed to accidentally spilled poison gas (her parents are also killed in the accident, making for a scene which is a little more emotionally intense than anything in FernGully. In fact there are several such moments of poignancy).
The three work together well as an ensemble. There is no clear single hero/leader figure. Abigail is capable of taking charge while remaining feminine, and without the annoying G.I. Jane syndrome which seemed to affect many heroines of the era. The two male members of the party are both rather overweight and hardly look like your typical hero material, but there is no cloying "chubby kids are ok too" nonsense. In fact, the film in general is just less hamfisted than FernGully. There is even a recognition that humans have changed their attitudes to nature and perhaps are no longer monsters - and of course the irony that the animals have to use technology themselves to complete their quest.
If FernGully had Batty, this movie has Michael Crawford, who is terrific as the elderly badger Cornelius (it's amazing to think this is the same guy who played the accident-prone twit Frank Spencer from the 'Some Mother's Do 'Ave 'em' TV series). The big difference here is that whereas Williams was largely holding Ferngully together, Crawford is merely the strongest actor in an otherwise good film.
'Once Upon a Forest' is pretty short, clocking in at about 65 minutes, but it's also a one-song movie, so you can probably add 10 minutes on for plot that doesn't happen when people are singing in your average Disney movie. Also the song is a good one, and handily, Crawford happened to be on hand to sing it.
A good solid movie, which like so many from the brief blossoming of 2D animation from smaller studios in the 90's, is unfairly destined to be a footnote to the Disney blockbusters.