Very nice
Ok this one here is "REALLY-NICE" a good background piece or something you could use inside an animation. "I-LOVE-THE-DETAIL" of the trees and the overall landscape you've achieved here. The sky is a bit baren but you can always fix that later with more clouds and such, but it still looks good without any of that. I like the hills you've seem to emulate inside the picture, at the bottom of it. It makes you feel like the trees are on a hilly area and that gives this some depth. My only suggestion was to add those clouds in and maybe a person by turning this into an animation.
~~THINGS TO IMPROVE ON~~
This one just needs more of a sky with clouds and such.
~X~