ests cover almost 40% of the European Union territory , and, with 75 forest types  and 81 habitats (Directive 43/92/CE), are crucial for the conservation of biodiversity in Europe. One quarter of European forests are protected, but only about 1% is left unharvested .
These figures underline why the maintenance of forest biodiversity in the European Union is based on the concept of sustainable forest management (SFM). Despite this, about 80% of the forest habitat types are in an unfavourable conservation status, and forest management is reported as their main pressure .
The existing SFM indicators for the biodiversity sustainability of forest management either account only for trees, or are indirect biodiversity proxies, often not tested or vaguely defined. This crucial gap stems from the lack of broad scale forest biodiversity data, with multi-taxon biodiversity usually not sampled during national forest inventories due to money and time constraints.
Recently, several groups of scientists from research institutions across Europe took up the challenge of multi-taxon field sampling through local or regional projects aimed at understanding the effects of forest management on overall ecosystem biodiversity. The BOTTOMS-UP platform of European forest biodiversity encompasses about 3,000 plots across 13 forest categories  and 13 European countries. For each plot, information on at least three taxonomic groups are available, besides spatial coordinates, individual tree measures, and information on forest management .
This effort will be used as a means and stimulus for upscaling ideas and actions performed at the local level on the effects of different management regimes and of specific good practices on several taxonomic groups, and on the identification of direct biodiversity indicators of management sustainability.
 FOREST EUROPE, 2020. State of Europe’s Forests 2020.
 EEA, 2006. European forest types. Categories and types for sustainable forest management reporting and policy. EEA Technical Report No 9/2006. EEA, Copenhagen.
 EEA, 2020. State of nature in the EU - Results from reporting under the nature directives 2013-2018. EEA Report No 10/2020. EEA, Copenhagen.
 Burrascano S., Trentanovi G., Paillet Y., […], Odor P., 2021. Handbook of field sampling for multi-taxon biodiversity studies in European forests, Ecological Indicators 132.
Re-building resilience in Europe's forest ecosystems: insights for solutions
Annemarie Bastrup-Birk (European Environment Agency, Denmark)
Multi-taxon conservation strategies are highly needed, but also challenging: examples from boreal and hemi-boreal forests
Joachim Strengbom (Swedish University of Agricultural Sciences, Sweden)
Trade-offs between timber revenues and biodiversity conservation shift for taxa differently affected by forestry in boreal landscapes
Adriano Mazziotta (Natural Resources Institute Finland (luke), Finland)
A European platform of forest multi-taxon biodiversity and stand structure data
Sabina Burrascano (Sapienza University of Rome, Italy)
A European series of forest stands of different ages and their multi-taxon biodiversity
Tommaso Sitzia (Università degli Studi di Padova, Italy)
With experimental approach towards sustainable forest management – upscaling local multi-taxon experiments to European level
Flóra Tinya (Centre for Ecological Research, Institute of Ecology and Botany, Hungary)
Habitat thresholds for forest biodiversity as recommendation for managers in Europe
Inken Doerfler (Carl Von Ossietzky Universität Oldenburg, Germany)
Validating forest biodiversity indicators with multi-taxonomic data: An Europe-wide analysis
Yoan Paillet (Inrae, France)
This symposium is based upon work from COST Action BOTTOMS-UP, supported by COST (European Cooperation in Science and Technology)
COST (European Cooperation in Science and Technology) is a funding agency for research and innovation networks. Our Actions help connect research initiatives across Europe and enable scientists to grow their ideas by sharing them with their peers. This boosts their research, career and innovation.www.cost.eu