hey
I think alot of jaggy pixels need attention, and some the highlights smoothed. Also some more attention to the lighting also. But yea, the shading looks a bit messy to me.
I really don't like the highlighted overlap or whatever between each stripe, and actually prefer the original striped tree.
I also think you should add some more branches with leaves right under, and maybe divide the top leaves up as has kinda already been suggested.
Anyhows I'm currently trying todo an edit for ya.
cya