Rot resistance (e.g. black locust, cedar, white oak) retained as sawdust?

Basically, the question is in the subject line. I've read that wood's durability typically boils down to a combination of 1) the extractives/compounds that help to deter fungi and other rot-inducers and 2) the density of the wood itself. Black locust seems to be an example of a wood that has both in spades and contributes to its superior rot resistance. My question is, how important is #2? I think there are some interesting applications for sawdust that is rot resistant (e.g. loose fill insulation in subgrade applications like a basement, when mixed with wood glue or some other binder could be an outdoors-compatible wood filler, I'm sure there are other applications) so it'd be cool to know.

Curious, maybe someone's accidentally left out a pile of pine sawdust, a pile of maple, and a pile of white oak and seen a difference in decomposition? Maybe some unintentional natural experiments going on out there? Just probing the hive mind for inklings of an answer :)

I feel that you have asked a great question.

I don't have an answer though I do know that sawdust makes a great insulating material.

I hope that someone has done some experimenting/or accidentally found an answer to you question.

Black Locust saw dust, mixed with a little garden soil makes an excellent seed stating mix. I never really examined it in regard to how quickly it rots but I "think" it does it pretty quickly when used like that.

The density plays a big role because denser woods generally have tighter cell structures, which can make them more resistant to rot and fungal invasion. The extractives are like natural preservatives that can fend off pests and fungi, but without the density, even the best extractives might not fully protect the wood from decay.
Regarding your sawdust idea, density would indeed matter. Denser sawdust might be less prone to quick decomposition compared to lighter, less dense sawdust. Pine, maple, and white oak have different densities, so their sawdust would likely decompose at different rates. Pine is lighter and tends to break down faster, while maple and white oak are denser and might resist decay longer. If you’re experimenting with sawdust for things like insulation or fillers, considering these differences could definitely impact the effectiveness and longevity of your projects.