I am not sure what really does it for me with this picture, there is no real focal point and the composition is very linear, but the texture of the ground and how it contrasts with the background is really intriguing to me
Rather than the 'light' being the theme of the image, its the shadows!
Just what's called for in this challenge!
The backs of the trees being so dark, and the grass having strong shadows help.
Good job keeping the focus on the shadow - it almost looks like a trench.
One nitpick - It would better if the shadow started from the coner of the image... **scratch that**** diagnoal from the corner usually works as the 'theme' is what the diagnoal leads the eyes to.
In this case, the theme *is* the diagonal shadow (or its part of the theme), instead of the tree it leads to.
This is a very nice shot, one of the better ones I've seen so far. The only change I might have made is move just a touch to the right before taking this so that the shadow runs from the left side giving a nice lead up to the treeline. Other than that, very nice. 7