Last stage, whopee. It's basically more refining (yes I do that a lot) with even smaller brush size, and adding some points of interest to make the tree more of an individuality. It got a few holes in the trunk, and some plantlife. Ideally, you would also finish the roots and add things all around them. Perhaps some extra moss on the tree, oh and the foliage - but I'm not going to do that for the purpose of this tutorial.

Make the best out of your imagination to make your trees live!