Blue tree foliage, as nicely rendered as it is, due to being cool hued makes a hole into the warmer ground, seems to be less high than it. Basic color theory: warmer = closer, colder = further. I'd suggest a retinting of that part.
no, helms crit is entirely valid. put your face 3 feet away from the screen. all but the highlights of the leaves will seem to come forward, the rest will seem to be behind the gjround.