98% of a trees mass comes from "carbon capture".
[1] http://www.carbolea.ul.ie/files/Biochar%20Swift%20Hayes%20Ch...
Don't burn it?
> or decays
In a healthy forest, a decaying tree is replaced by new growth, and part of the carbon is captured into soils (including high-carbon peaty soils, which is what's under the forests currently being burned for palm in south-east asia), so a growing forest is a large carbon sink and a stable grown forest is at best carbon-neutral, possibly a small sink depending on its composition.
> Turn it into a mineral and you have indefinite stability.
The lithospheric carbon cycle is still a cycle[0]. Lithospheric carbon gets released by volcanoes and by acidified oceanic water.
[0] http://earthobservatory.nasa.gov/Features/CarbonCycle/page2....
I look forward to our descendants' giant cockroach overlords