Nice detailing and composition overall, with a little bit of work this could turn out really good.
I'm going to point out a few things that I think need some attention, please take this as constructive criticism as relatively minor tweaks could vastly improve your images.
The main thing that stands out to me are the colours in the scene. If you're working on a render, I'd recommend checking how it looks in black and white every now and then. If the render looks a lot better in B&W than in colour, there's definitely something off with the colours.
In your particular case it's mainly two things IMO: an overall over-saturated image, and vegetation that have colours/textures that don't match well. They have radically different hue and saturation values, and I'd try to pull the colours a lot closer together.
I have attached a quick post-pro attempt in Photoshop to illustrate what I mean, although all of these things could of course be done in the scene itself.
* The first thing I've done is a bit of a trick, really. I have pulled the "Hue" values of the yellows (mainly the grass) slightly towards green, and then pulled the hues of the greens (mainly the small pine tree) slightly towards yellow. That way the colours match better. In similar fashion, I've then desaturated and darkened the reds to give the bridge a more natural colour.
* Then I desaturated the whole image by a fair bit, and instead boosted the brightness and contrast significantly, to prevent the image from looking washed out.
* Lastly I added some vignette, to give the natural focal point of the image some extra attention.
Please feel free not to agree with these things! Also let me know if you want the .psd file for my edit to have a closer look (don't know how handy you are with post production).
Keep it up!