I recommend that you both take a look at a copy of Agee's "Fire
Ecology of Pacific Northwest Forests" and then try out anything by
Stephen Pyne. Good rainy season reading. Fire occurred (and still
does) at varying levels of intensity. DF survived some while dying
from others. I habitually check out big stumps (yes, many DF got
larger than 6 feet, although 10+ are probably Spruce) to find the
burned rings. Even in the depths of the rain forest, sign of old
burns are easy to spot on Red Cedar.
They may not have burned that intensely, or that often on the human
time scale, but looking at old stumps you can see that fire was COMMON
FOR A TREE even along the coast. What makes anyone think the flames
stopped at the edge of those "prairies" every year? Ever had a dry
year on the "we(s)t side"? The locals enjoyed the berry production
from those escapes, and it made getting aound a lot easier. It also
encouraged growth of many herbal and useful plants, which seem rare
now that anthropogenic burning is outlawed.