Some will be sequestered in this way, but how much and under what conditions? Tropical rain forests, for example, are known to have very poor soils despite the massive amount of biomass growing in them. Almost everything is recycled back into the forest very quickly. Clearly, no significant accumulation of sequestered carbon is occurring there. On the other hand, peat bogs occur because dead plant matter falls into a low oxygen environment and doesn't really decay, so there can be a build up of sequestered carbon there, but that is rather specific conditions.