First let me say i am big fan of trees as body art. This is piece is fantastic as well!
The placement of it on the arm/shoulder/neck is perfect and i'm sure most tree tatts i've seen have been on the back or arm. My line of vision follows up as it should and it works perfectly with the additions of the birds fluttering up.
The tree and roots are well defined but the contrast from the tree to the leaves (clouds?) is too much. The tree is too dark for the leaves or the leaves are too light. Either way i would have liked to see a little lighter bark so i could make out more definition.
A creative suggestion, maybe have a bird or 2 as if they were still in the tree and coming out.