there was a big burn around the mapleton to swisshome area in the early 1900's - 1930s.  in many places the old growth had survived  and thrived because the smaller trees were not there vying for food and sun.  lore out that way was that the various native peoples would burn out the underbrush in controlled fires on a regular basis. it opened it up for hunting and prevented big raging fires because the fuel just wasn't there. they also lived as far up as possible to avoid the air inversions.. valley of sickness is what i was told it was considered and tagged.