This is a very nice, natural-looking scene. I think it only needs minor tweaks to get near photorealism (IMHO). I would suggest slightly desaturating some or even a majority of the ground cover and foreground plants. Right now it looks like all the plants are very "rich" and saturated, it seems like a very, very healthy environment, perhaps too healthy.
I think having the trees slightly brighter than the ground in terms of color would add to realism and also give a nice compositional range, whereas now there is more tonal similarity throughout. I also think some added break-up, more of a slightly "patchy" look in some of the ground vegetation would add to the realism. There is a little bit of break-up now, but even more would be helpful I think.
Whether you make further adjustments or not I think this is great!
- Oshyan