Ain’t that the truth! I spent many of my formative years in Wintun/Modoc country of N. California, and was well aware of that. In the case there, it wasn’t for planting, but to keep large brush & encroaching scrub down. That encouraged growth of new browse & increased the amount of transition forest areas for better hunting.
Also, though, when ‘slash and burn agriculture’ is mentioned in social studies, the implications are not mentioned, and the kids never think about it. The impression left is that small plots around a village had brush burned off of them for planting of ‘the three sisters’, and all lived in peace and harmony, at one with Nature, until the Evil White Man came.
Exactly, you nailed it. It was to increase and promote better hunting areas. And, farther east, to increase grasslands for buffaloe and other prairie game herds (same thing essentially, just different target animals).
Slash/burn agriculture was/is only used in tropical forests, and not in NA. And the North/Central American Native Americans had very a sophistocated agriculture anyway, much more advanced than slash/burn.