Nice tree. You've done a good job of capturing that canyon-rim feeling.
I might want to see the upper canopy brought down closer to the lower primary branch - right now, the division between the two makes the tree appear to fork and leaves the eye unsure which line to follow.
I'd personally rather see the tree centered on the stand, for the reasons that Attila lays out so nicely in his article on the Role of the stand
Finally, as a minor technical comment, be careful when using photoshop to paint out spots or highlights on the black background. Your background isn't quite black whereas your blackout spots are, leaving funny black circles. I try to either adjust the curves to set the background to pure black, or, alternatively, to clone over the spot from a nearby region of the same not-quite-black hue.