This cluster project will bring together a large team of forest researchers to tackle the very relevant and timely question of biodiversity functionality. The network that will be further developed during this cluster project will be truly interdisciplinary: scientists from a range of disciplines (forestry, biology, hydrology, ecophysiology, socio-economy, etc.) will be attracted to the network and be invited to participate in the field experiment. These scientists from multiple disciplines will allow building a complementary view on the functional aspects of forest biodiversity. The network will furthermore build bridges between science and policy. On the one hand, the cluster project will synthesize and disseminate the existing knowledge on the importance of tree species diversity for the provisioning of forest ecosystem goods and services and on the other hand the project will allow establishing a unique and novel experimental approach, which will form the basis for long-term top quality research on forest ecosystems in Belgium.