chemicals in tree bark compared to wood

I burned tree bark in the fireplace for the past week to see how it burns relative to wood.
But what I noticed most of all is the amount of ash left behind by
bark. It is about 3 times more ash than burning wood.
What is in bark that it leaves so much ash behind?
Archimedes Plutonium whole entire Universe is just one big atom where dots of the electron-dot-cloud are galaxies
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