Excellent job on the background and great Idea with the ropes. I think I've seen the bent pipe method before but you did it well and the robes really add to the finished effect. I think this is one of if not the most truly natural backgrounds I've seen. I mean thats is really what you would see, an eroded out bank with tree roots next to a stream...Probably a good place for finding frogs too
My only suggestion would be that it might be interesting and add to the effect if you could slightly alter the color of the coating on the ropes...either do the pipes in grey and ropes brown or vise versa...or just 2 shades of brown even.