Shame Poser doesn't have something akin to instancing or similar to Carrara's surface replicator for vegetation. Imagine you will need to fudge with some transmapped billboards for plants, trees, whathaveyou. In any case you'll be dealing with a lot of transparencies I imagine, which with GI can become something of a grind. Howie Farkes country lane for Carrara looks similar to what you describe but of course we're talking about Poser, a figure rendering app...