Inside its own world. 
Where a whole world exists within the tree.

I started building a matchstick house back in 1977 and have carried on building it for thirty years. It still isn't finished and probably won't ever be. 
I think the idea had its origins in the Wizard comic from the late 50's, early 60's. It was an all words comic, but my mum used to like reading it and some of the stories filtered through. 
The story that must have soaked into me was of a tribe of jungle dwellers who lived in a huge tree. - - a whole clan of them. 
I can't remember what they got up to (maybe because I preferred looking at pictures). But the concept amazed me!