Ben, nice piece but you have missed perhaps the most important factor of all, one that is almost never discussed for the obvious reason that it gores many oxen. That factor? the century and a half of logging practices that were a primary reason for the Forest Service AND the fire suppression policy in the first place. I’ll have to check but I think that 90% or more of the original mature forests in this country have been clear cut logged, and what grows back after clear cutting is in no way what has been removed.
I have a Medium piece on this topic (Logging’s Dirty Huge Secret) but in shorter, mature forests are far more resistant to the mega fires we see today because of the way they have grown. In a mature forest the canopy is high, replacement trees have to race upward to fill the openings in the canopy, the shade thrown by the canopy keeps the volume of woody shrubs and brush down. When fires DO burn through they encounter mature tree trunks with relatively thick and fire resistant bark and few low branches, they burn laterally and often don’t bridge to the crown. Further the shade created by the crown and the deep forest “duff” act to maintain moisture both as sponge and shield from evaporating heat and sunshine.
Contrast this to the regrowth of clear cut stands. When all or most of the trees are felled the canopy is lowered to ground level. The replacement trees throw out lateral branches immediately. They are, from the seedling up, competing to monopolize the available sun. As they grow they continue to lift the crown but they leave attached to their trunks a trail of heavy branches that eventually bridges from forest floor to canopy, dead dry branches that take decades to “self prune” and then fall and accumulate on the forest floor as potential fuel. This is a perfect fire ladder to take a ground fire up to the crown, which is composed of highly flammable needles and smaller branches.
Sometimes the drying out of the landscape from felling the mature trees precludes regrowth of forest at all, or delays it by decades or even centuries as brush dominates. SOMETHING is going to grow back in the place of a mature forest and EVERYTHING that does grow back is more flammable and likely to promote firestorm activity. Obviously neither the Forest Service nor the logging industry want to discuss this reality; the FS is already being blamed for fire suppression, the loggers want to go back to taking the valuable mature trees and don’t want to mess with the rest other than to cut them to get them out of the way. Bottom line? Without commercially unviable thinning of unmarketable trees and preserving the VERY valuable fire resistant mature trees you can’t cut your way out of fire danger except for concentrated efforts around communities to save developments.