The background to establishing the Concerted Action (CA) was the special situation of forestry in mountainous areas in Europe. Mountain forests are distinctive from forests in the lowlands with regard to their ecological and socio-economic implications (table 1). Mountainous forests differ specifically from forests at lower levels in site conditions, tree species composition, structures, and stand dynamics. They have a higher risk of damage by natural disturbances. Mountain forests are typically not only used for private goods like timber production but also serve for public purposes such as protection against natural hazards, biodiversity, carbon sequestration, recreation, etc. Furthermore, the improvement of their economic utilisation through higher mechanization is limited by steep slopes. Therefore, these forests require other management concepts than forests in lowlands. [...]