Hahaha, the dome is there initially because I want to incorporate a story into the game but decide the scrap it.
The story goes like this: You are living in the future and you are tasked to chop the trees down in the dome. The plot twist is that the dome is a time chamber which speeds the time of everything inside. So the tree will grow significantly faster and you realized you are getting weaker and weaker and eventually dies of old age.