
Made a quick edit addressing the things I think require the most attention.
Here's the things -
You have a shadow going around almost all of the tree and the rocks there, which makes no sense, since the top of the rocks would be higher than the ground and you couldn't see the shadow there, same for the tree. Instead maybe just try to enlarge the shadow on the lower part a bit more instead of putting it all around the trees etc.
The trees also have some colours that I dont think are required, the light brown and even the darker brown colours(which I did not remove). Plus you could maybe make the tree leaves look more like actual leaves.