The reason jungle movies are usually shot on stages is because stages are easier. But there's a problem with easier. It doesn't look hard.
Now I'm not saying this because I'm a disciple of Lars von Trier –– as a matter of fact, I happen to think his entire Dogme 95 manifesto is a bunch of crap. (As he seems to, too. Watch any of his films and just count all the times he breaks his own rules, starting with #10.)
But where I agree with him has to do with intention, sort of. His position is that film should be honest; mine is that film should feel honest. To that end, I'm okay with shooting a stage to look like a jungle. Just make it look like a jungle.
All of it.
A smooth floor is a dead giveaway that your actors aren't really outside. And even if you can't see the ground, you can tell by the way they move.
I've chopped through my share of jungles. Trust me, you're stepping in –– or trying to avoid –– a bunch of really interesting things down below knee-level.
Peter Jackson knows this. Now you do, too.