IMO, there seems to be a distinct contrast in style between various elements; ground, tree trunk, and canopy.
The only thing that seems to be separating the trunk from the ground is the outlines, I feel as if the piece may be improved with the removal of the outlines. Nothing else has outlines, thus far, so it seems out of place. Although, some color tweaking may need to be done to further separate it from the dirt.
The canopy seems to be very unrefined, and painterly. Don't get me wrong, I think it looks lovely, but it's very much different than the other 2 elements in this picture. The ground is nice and detailed, refined, and sharp, whilst the canopy is not. I think a different leaf technique is needed, unless you want to fiddle around and make the ground match the style of the canopy.
It doesn't matter, I love both styles, I just don't think they are working together nicely atm.
Keep up the good work.