You may have misread my statement. Dense evergreen forests in the valley weren't natural even before tribal settlement. The tribes innovated by practicing contr

You may have misread my statement. Dense evergreen forests in the valley weren't natural even before tribal settlement. The tribes innovated by practicing controlled burns, and part of this was due to wanting to survive; fires caused by lightning and other non-human causes are rare in the valley, so the "natural" state was catastrophic fires every decade or so as forests encroached and provided tinder.