Using the same color, make roots growing out of the bottom of the tree a little.
Using the smudge tool set to 78% strength on “beech” layer to fill in roots.

Using color #3Z2B00 draw curving “stripes” across the trunk. The lines should be widest near the edges, and taper off in the middle.

Color right above the lines with color #E5CA90. This will finish the bark effect.

Make a new layer above the “foreground trees” layer, and title it “foreground trees outline”.

Outline the two front trees with color #291000 and a size 20 opaque brush.

Using the same color and brush as before, outline roots growing out of the ground around the two large brown trees. Make sure now to close off the shapes of the roots, but rather leave gaps, so that they will appear to be growing out of the ground rather than sitting on top of it.

Now use color #293BOE to block in the roots. This will work best if done on the layer below the outline.

Now use color #4D2600 to block in the shadows on the roots.
