This is wonderful! But rampant with jagged pixel clusters. Edit including ndchristie's points:
Yeah, I kind of screwed the priorities in the piece up with my contrast. But I think in some places I improved it (bushes, rocks, walls, sky).
Ramps are very flat, hue-wise. Just playing with the colours and tidying up the jaggedness brings out a tonne of goodness in this piece.
Other thing, on the tree trunks you have these large flat areas of highlight that go almost immediately into shadow. There's much more potential for defining the form if you more carefully spread your values. Blend the highlights gradually across the form into the shadow.
