Database of European vascular plants red lists as a contribution to more coherent plant conservation

Abstract

The European vascular flora is estimated at more than 20,000 species, with the highest diversity concentrated on the Iberian, Apennine and Balkan Peninsulas1,2. Although the European flora represents ~5.7% of the global plant diversity, 44.9% are estimated to be threatened with extinction within Europe2 and this number is similar to the recent global level predictions for extinction risk3. One of the main aims of plant conservation is the evaluation of the extinction risk of each taxon through a conservation assessment and assigning a red list category to reflect its conservation status4. This process is widely referred to as threat assessment in determining the threat status. This framework was first established in 1964 by the International Union for Conservation of Nature and has become the globally accepted method for assessing the extinction risk of a taxon (IUCN, https://www. iucnredlist.org/about/background-history). Its guidelines are applied in conservation assessments at different geographical levels, but they all essentially aim to determine how close a taxon is to being extinct: global, continental, regional, national and sub-national. Globally, biodiversity is declining at an unprecedented rate, and conservation assessments have become the most important source of information to produce the Red List Index (RLI) used for monitoring the aggregated or overall extinction risk of taxa over time5. The index indicates a rate at which the taxa move towards or away from extinction risk. The IUCN uses a series of numerical thresholds, based on measurements of taxon abundance and decline, to assess the risk of extinction of a particular taxon and assign a conservation status using a red list category. The criteria rely on taxon data such as population size, trends in population growth, geographical distribution, and threats to the taxon or its habitats, etc6. There are 9–11 red list categories in the wider global to sub-national usage to identify how close a taxon is to extinction. Taxa in Critically Endangered (CR), Endangered (EN) and Vulnerable (VU) categories are collectively described as ‘Threatened’ with a high risk of extinction. Although most European countries used the IUCN standards for conservation assessments, this is not the case for all countries. Some relied on older versions of red list categories7 (e.g., Malta – “Rare”), used criteria intended for global assessment and not for national level8 or slightly adapted the existing categories or created entirely new categories (e.g., Slovenia - O1 as a subcategory of the old “Out of danger”). There are several inconsistencies in threat assessments between countries, hampering efforts to assess meaningful trends across countries or to create a unified list for Europe. Significant gaps exist in the availability...