I think the leaves and grass have too much detail vs. the bridge and the rocks being very diffuse. All this makes the image look a bit dark as well, maybe you could have a double layer of it and overexpose one of them, and then play around with the fill?
A bit of playing around with the RGB settings, as well as adding more diffent colours to it might add ma bit more realism to the pic. Good effort either way; I'm quick to criticise/advice, but I doubt I'd have the mindset to go and do it starting from zero.
Lastly, try making the moon less lighted (words fail me)... an outline of it would make it much more realistic.-