I started with this one beginning with the closer stand of trees on the right side.
I put the foliage onto the trees and added more details to the tree trunks and branches.

I finished this section of trees by putting a few smaller young trees in around the base of the mature trees.
From there I moved to the other side of the drawing and began to put in the start of the forest at the lower edge of the field.
I will post this drawing at a later date once more work on it has been completed.