Great image, Choronr! I really like the soft shadows and color settings, makes it almost perfect. I double Kadri about the trunk, the texturing isn't right. I also think that the water should give the surrounding dry mud a little more wetness than it has now. A scattered reflective shader might do the trick, but it's hard to restrict it to the direct surroundings of the water plane.
Another trick I found out a while ago is to feed the ground displacement into the lake (before the water shader). The water plane will follow the terrain then. With a surface layer and a subtle dose of smoothing after that and perhaps very tiny height control by distribution shader you might pull it of.
It's what I did here, you can best see it at the left side, where there's a smooth puddle surrounded by wet mud. But the image itself is not very nice.