I read a thread on the weekend where someone was all against using deadfall for building, and recommended instead to buy 2x4's. The reason was that putting deadfall up in the air would take away from a forest floor's nutrients and the forest was some closed loop or something. I disagree. Wood on a ride lasts max 2-3 yrs, so you're only borrowing the tree food for a couple of years, after which you return it all mulched up. Trust me, the trees will not notice!!! Plus by simply hanging out in the forest you take all the carbon from that carbohydrate in your breaky and you donate it to the trees every time you exhale. You can more than make up for the fact you're borrowing some wood from the forest floor by taking a piss by the trees. Piss has nitrogen in it which trees use to make amino acids to grow. As for not nailing stuff to trees cause it might hurt em
I say if the tree is big enough and you need to put a nail into it, just do it!!! Trees have been evolving over milll's of yrs to deal with bastards like woodpeckers and beavers mashin holes in em, they can handle a few nails! Just make it up to the tree by exhaling lots of CO2 and taking a good piss.