The Sonian forest reserve in Belgium is a rare example of Atlantic beech forest, as is evident from its status as a UNESCO world heritage site. In such a natural forest, high amounts of dead wood are an essential component and key to the survival of many organisms. Fungal communities on dead wood are highly diverse and play important roles in the forest ecosystem. In 2001, decaying beech logs were surveyed in the Sonian forest as part of the first broadscale, international initiative investigating fungal communities on beech (EU NAT-MAN project). In the current project we aim to combine these datasets with resurveys, incorporating extensive existing datasets on dead wood properties, chemical wood composition and ectomycorrhizal fungi. We will analyse the development and succession of the fungal community during decay by surveying subsets of the exact same logs. Potential shifts in the fungal community as such will be evaluated by comparing similar subsets of logs over the two sampling periods. This will also be done for Nat-Man sites in Denmark and Slovenia. Furthermore, the surveys will be expanded to include fine woody debris, and fruitbody surveys on the logs will be supplemented and compared to results from environmental sequencing. In this context, additional focus will be given to ectomycorrhizal fungi occurring in the late decay stages of the dead wood, and their potential linkages to ectomycorrhizal fungi that are essential to natural regeneration of beech seedlings.