Here's what I like to do to not only keep poly counts low (considering your use of Poser folk) but to give myself a bit more control over placement......

I use a plane object and place an ecosystem of whatever on that. Then I make the plane invisible and save the whole thing out as .vob. I usually make 3 or 4 for variety.  Then, I just load the .vobs and place them, scale them, rotate them any way I need to.

This way I avoid a lot of carpet polys that the camera won't see anyway and I can move my ecos around.

M