Major disadvantages of give pieces - lack of adequate lighting.
Square artificial objects may be a better decision.

Yeah, I think you're right there Sohei.  Also, after adding the detail on top of my blocked out cheesy shading, i'm finding it pretty hard to re-light stuff and not wash away the details...  Thanks for the feedback and, I have to say, your trees are awesome , I really like how the sunlight almost shimmers through them.

Kitty, I feel guilty since I'm using 6 shades of green, and I wanted 4... Maybe I will try to desaturate the image and recolourize it.  Sohei is right though, I just sat down and started pushing pixels around without much thought, and while I'm pleasantly surprised how it turned out, I probably should study lighting and perspective a bit more for my next go. 

Thanks for the feedback peeps!