There was a cartoon that was on in the late 80's and early 90's about a bunch of little critters that lived near or in or under a big green tree. I wish I could tell you more or be more descriptive but I was very little when I watched it. I have ruled out the following TV shows so no need to mention them:

Under the Umbrella Tree
The Noozies
Gummie Bears

I realize I gave you basically nothing to work with, but my fingers are still crossed. Thanks!

Maybe The Wuzzles?