(http://johnsonm.com/Art/Dawn_Forest.jpg)
Based on the Golden Forest tutorial, this took 9 and a half hours to render and was totally worth it.
I would try adding a second sun light. Turn off the shadows, and place it higher up above the sun you have here. Keep the strength of the second sun low, 0.2 maybe. It would illuminate the foreground grasses for you.
I like the effect you are attempting. I hope you keep working on this, it is difficult to achieve without post image processing.