Why is that? Sap content? I just started reading Hoadley's "Understanding Wood" [0], which has gotten me interested in wood's characteristics.
[0] https://www.amazon.com/gp/product/1561583588/ref=ppx_yo_dt_b...
[0] https://www.amazon.com/gp/product/1561583588/ref=ppx_yo_dt_b...
Douglas-fir trees have very thick, insulative bark that prevents the live tissue from dying as readily when there's fire. Sequoia trees have cones that are glued shut by resins that only melt after a hot-enough fire, so they can then land and germinate in burnt-over ground.