Well, it belongs to a friendly gnome who lives in Honey Hollow!
This gnome has decided to trade some of his treasure with you. So please make sure to bring something extra special to trade. Mr. Gnome likes to disguise his door as just a regular old tree, to keep his privacy and also to keep the treasure safe. So please make sure to hide the door again really carefully after you have made your treasure trade!
And remember to thank Mr Gnome for being friendly, and for trading his magical treasure with you!