When you harvest a mature plantation you let the leaves/needles shed and return to soil as they contain most nutrients.
The stem can be bucked into logs and sawn into boards and made into structures that can last many hundreds of years The sawdust can be compressed into pellets
the branches devoid of leaves can be chipped and used as biomass
The bark can be mulched and used in gardens
replant the forest and let it convert more atmospheric carbon to wood using water and sunlight
