I thought about the same thing, but what we are using in the fish tanks has normally already been processed, by Ma nature or by man... De barking is one, and like Mopani wood it is dense, it doesn't float and there has been alot of time underwater in nature (the biggest filter of all), sand blasted and all the crud, minus some of the tannins, has been leached out of the wood, making it suitable to be in our little part of nature. Beneficial bacteria can only do so much.
I would like to see more postings on the wood that CAN be used (oak leave?), there have been some branches that people use in there tanks that are considered safe. Is there any good listings of such woods? I know the obvious of soaking for X amount of time, I'm cool with that, but I want to see more mangrove branch biotopes and how we can achieve this. I have rarely seen live products that replicate this, only those expensive plastic ornaments.
I know I have seen a member do just this...180G(IIRC) white to tan colored sand and there is a branch as the centerpiece...