Preparing found wood/branches

I am going to be changing my showerstall growing chamber over from greenhouse style (all in pots) to an enormous natural vivarium with most plants mounted to the branches, cocopanel background, etc and some growing in a substrate base with a false bottom.

I can get some wood from the Reptile shops but it's expensive because I want 6+ foot branches. There are 10 miles of bicycle paths through woods behind my condo complex. There's plenty of moss covered fallen branches down in the ravines. I was wondering if there would be any harm in using these fallen branches. Would I need to treat them somehow? Like soak them down with fungicide and insecticide? If possible I'd like to let the moss and lichens & mushrooms stay alive on it and not use anything too harsh.

any ideas? thanks folks!

I have collect dead wood from the wild, after getting premission from the landowner, and have had very little trouble. You could put them in the chamber alone for a while and watch what grows.