Perspective's off. If you plotted this out you'd find that stuff shrinks as it nears the horizon a lot more than you think.
Watch out for tangents in the trees.
Also not sure what the speckles in the sky are all about. But regardless of what they are, you should've done the sky on a separate layer under the trees so they wouldn't look like a hasty afterthought. It's clear that you put them in later and were trying to carefully put speckles in between all the trees. Or you should just not be afraid to repaint the trees over the speckles.