The forests in western Europe are storing more carbon in their soils over time. This is because the trees are getting bigger and producing more litter, which adds carbon to the soil. By studying data from 1950 to 2040, researchers found that the soil carbon stock increased steadily. In 1990, the soil was already absorbing 32-48% more carbon than the trees. By 2040, the soil is expected to absorb even more carbon, becoming the main contributor to the forest's carbon storage. This increase is mainly due to the increased litter fall from living trees. Forest management practices, like choosing tree species or harvest methods, can help control the soil carbon levels. However, there is some uncertainty in the estimates, with a potential overestimation of 35% or underestimation of 50% in the soil carbon sink.