Well, a few suggestions... you may want to put some rivers leading into the lake, or it'll run dry pretty fast.
The shading on your mountains looks odd, like you've added shadows to the side of the mountains facing the light source (the left side, it'd seem) Maybe you were trying to blur the edges a bit and hit the layer rather than the mask? I think you should try to blur the edges, the mountains are pretty "glued on top" rather than looking like part of the land. Some foothills could help here as well.
The forest is nice, and your general colour scheme too. I think you could improve the southern forest by blurring the edges some more, and maybe add a drop shadow?
Oh, and the "wooden" border? Bleh.