Thanks for the positive comments guys and sorry for the late reply, I have been out of the state for a while.
To answer few of your questions
1. For the trees, I have used evermotion archmodel vol 1 tree collection for corona as pointed by Yagi and yes I did tweak the shaders to make them look good.
2. lighting is just one hdri , all with dof, glow and volumetrics baked in corona frame buffer.
3. very minimal post, just the usual passes I use (reflection , direct, transulcency,abit of curves, color balance and little glows)
4. some of the assets in the scene I have modelled them myself.
5. Rendered in Corona 1.5.1
Thanks again!