Chile John, you are absolutely right about 100 years of fire suppression causing problems.
I was told by "old heads" that one of the reasons the D&RG often didn't use spark arrestors on the 480's and 490's was that the MOW people actively cut, poisoned, or whatever, the brushy vegetation along the track. That way when cinders started small fires in the grass they would either die out harmlessly or could be relative easily extinguished by a section man.
I remember seeing ample evidence on the Silverton Branch in the 1960's and early 1970's of "defoliation" along the ROW. Of course, that became "politically incorrect" and now the D&S has to use those stupid Ridgway arrestors. Oh, for the good ol' days, sometimes, at least.