Hello, it's been a while since i was here.

Now, I have this scene where customer is asking me to create lots and lots of trees. I made them using paint effects and converted them to polys (like 8k polys per tree),and if i render scene that doesn't show distant tree, it's all ok. But if i point camera so that it show distant trees too, maya just stops rendering. The problem is, that i'd like to render nice, raytraced shadows. So, one thing that comes to my mind, is something i know games have.
So, is it possible, when you render short animation with this scene, to tell renderer to render only tree that are close to camera? If not, what other option is to render it?
I'd use paint effects, but they don't have raytraced shadows.
So, any suggestion?

---edited---
Also, i don't know much about render layers, but would this help?