Authors: Paillet, Yoan; Aszalós, Reka;Brazaitis, Gediminas;Campagnaro, Thomas;Chianucci, Francesco;Ciach, Michał;Doerfler, Inken;Gültekin, Yaşar Selman ;Haeler , Elena;Heilmann-Clausen, Jacob;

Most forest biodiversity indicators are based on existing data from national forest inventories. They have been used for several decades to assess the state and dynamics of forest biodiversity, notably through Forest Europe's initiative and reportings. Although valuable, these indicators are essentially indirect and evaluate habitat quantity and quality rather than biodiversity per se. Therefore, their link to biodiversity may be weak, which decreases their usefulness for decision making for biodiversity conservation.
Within the framework of the COST Action Bottoms-up CA18207, we gathered data on multi-taxonomic biodiversity and forest structure across more than 3 000 plots in Europe. We hypothesised that no single biodiversity indicator from Forest Europe is able to represent all biodiversity, but that several indicators would reflect habitat quality for at least some taxa in a rather comprehensive way (e.g. saproxylic species).
While these indicators have been chosen for their availability and the fact that they are understandable to most, our analyses show that there are still gaps in the monitoring framework, and that monitoring certain taxa (groups, species) along with stand structure is necessary to support policy making and tackle forest biodiversity loss at the large scale.