what I really like, is that the foreground is light, then you have the darkness of the trees, that leads back to the light, that progression is very nicely presented. Nice image.
I also contemplated the square crop, but then I noticed the S-curved shadow path leasing up through the trees to the sky.
The shame at this size is that you really can't clearly see the other photographer with camera and tripod on the other side of the tunnel meandering on his own path.
I made a 30" print of this to hang in my office and everyone noticed that guy....