The Indians burned off the forests annually just about everywhere. Burning the underbrush does not harm the established trees unless you wait until the underbrush is very dense, which it is in most of the American forests now due to diligent fire control. The 17th century settlers in New England marveled at the open forests that you “could march an army through.” They also thought the Indians were crazy, burning the forest every year. And the Great Plains- they burned off the grasslands to improve pasture for bison and other hunted large animals.
Back in 1876, CRAZY HORSE attempted to burn the US Army out by setting almost 200 square miles of grass, forest and coal seams on fire.