Forests contain more carbon (C) in biomass and soils than is stored in the atmosphere. Consequently, forests are at the forefront for C sequestration and storage in the framework of climate mitigation. The European Union has recognized C storage in forests as one of the key policy options to achieve climate neutrality by 2050.

To accomplish this objective necessitates implementation of efficient and effective forest management measures to enhance the C storage capacity of forests. However, previous studies on the impact of management measures on forest C storage mostly occurred in single forest and/or focused on one ecosystem component. Therefore, there is paucity of robust and generalizable information about the impact of key forest management measures on C storage and distribution in multiple forest ecosystem components to guide forestry in Europe.

This thesis investigated the impact of tree species identity and mixing on C storage and distribution in aboveground woody biomass, coarse roots, and soil ecosystem components in 21 forest triplets (two-species mixed forest and their respective monocultures at the same site) in seven European countries. The triplets consisted of Scots pine, European beech, and Oak.

The broadleaved forests (European beech, oak) increased C storage in above and belowground woody biomass more than Scots pine, but the opposite was observed for soil C storage. Considering total C stocks (aboveground + coarse roots + soil), the mixed forests were at least equivalent to the most performing monocultures, implying that mixed species forestry may not compromise total C storage.