From a wilderness survival perspective, this is what I think to be germaine. When in the habit of accessing public lands, it should be with the notion to leave little or no trace. The idea being that your excursion is under enough control that you can minimize the impact to the environment by adequately planning, preparing, and resourcing for the endeavor ahead. Therefore, practice of primitive skills can be under those controlled conditions wherein you provide the necessary materials and methods that would effectively isolate your interface with the environment to a suitably minimal degree, such as bring your own twigs and branches and firepan with which to practice your primitve fire making skills upon. The idea being that you are practicing technique, which can be done at home as well as in the big woods, so no need to bring your mess to bear on the public domain any moreso that what would happen in your own backyard. Admittedly such actions, even when properly planned, resourced and controlled, will still have some effect on the environment as a whole, life in general seems to be that way, so the idea is to do it and do it efficiently.

Now, when the need for primitive skills becomes a mandatory effort for survival, your controlled practice will not only help secure your welfare, but aid in keeping your efforts more efficient and less of an impact to the environment as well. Lessons learned in practice can be applied with more of an aspect of environmental preservation as well as self preservation, although admittedly the environmental considerations must take a subjugated priority to those of personal assurance. Legal issues are to be even less considered, though wanton disregard is likely not warranted.

So, whether I should find myself lost in the National Parks somewhere, or the National forest, or BLM land, or DNR land, or whatever public land from which self egress is not going to likely occur, should I from my wealth of experience in practicing primitive skills and some sensibility determine that a tree needs to be cut down, or an animal needs to be killed and consumed, I will do what needs to be done to ensure my survival, and any environmental impacts I might create or laws I might happen to break are simply not going to be of significant consideration at the time. Nice if I can comply, but not much of a factor in the decision making process at the time.

Practice is one thing, doing it for keeps can mean a whole new set of rules, or maybe none at all.