> “Our results demonstrate that the above-ground and below-ground parts of a tree follow separate calendars, allowing for underground growth to be prioritized in winter and aerial growth at the beginning of spring,” says CREAF researcher Paolo Zuccarini, a co-author of the study. This divergence could offer a strategic advantage: in winter, while the rest of the tree is dormant, its roots store reserves of carbohydrates and nitrogen-rich substances, such as proteins and amino acids. Thus, when the tree ‘reawakens’, it will have enough nourishment for leaves to bud and photosynthesis to resume, which is essential for trunk and branch growth. “It’s kind of like having building blocks ready to use in the spring, when the priority is to produce leaves so that photosynthesis can start again,” explains Zuccarini.

Okay this part makes sense.

> Its findings suggest that forest soils have a greater carbon sink capacity than was previously believed, as they accumulate carbon all year long rather than only when trees are more active and their leaves are photosynthesizing.

This does not. They're not accumulating carbon in winter because they're not photosynthesizing carbon dioxide into glucose in winter. They're using stored carbon to continue cell division (not to mention bribing bacteria & fungi to build a rhizosphere with which to harvest nutrients).