7 to 9 percent of all European vascular plants are globally threatened

How certain is the continued survival of animal and plant species? How high is the risk that they might become extinct? The answers are collated in regional, national and global threat assessments; known as ‘Red Lists’. Legislators and, in particular, nature conservation organizations make decisions about specific conservation activities based on these lists. The problem is, however, that although there are many national Red Lists available, they are often not being integrated into the global Red List of Threatened Species by the IUCN (International Union for Conservation of Nature). Despite being the most comprehensive global list available, the global Red List still lacks threat assessments for almost 90 percent of all known plant species – a substantial assessment gap.

An international research team has now addressed this assessment gap for European vascular plants, namely most plants except mosses, algae, and lichens. It established that seven to nine percent of the European vascular plant flora is globally endangered. This is because these species occur solely in parts of Europe and are endangered in every part where they occur. Seven to nine percent corresponds to about 1,800 of the estimated 20,000 to 25,000 known European vascular plant species. Of these 1,800 species, 83 percent are not yet listed on the IUCN global Red List.

The results are based on a novel integration of data streams on the global geographic distribution of vascular plant species and national Red Lists from 37 European countries, spanning a period from 1999 to 2020. The researchers noted that national Red Lists typically include only half of all plants occurring in a given country, and therefore the team's findings are conservative estimates.

The IUCN list for the major vertebrate groups has been completed decades ago. “But this is not the case for plants,” says Hanna Holz, a biology MSc student at the University of Halle and first author of the study. “Such data gaps can be disastrous because they lead to uncertainties in priority setting in international conservation policy,” says Holz. “Our findings help update and expand the most important instrument in international conservation policy.”

The United Nations Convention on Biological Diversity (CBD) set itself the goal of compiling a comprehensive list of endangered plant species by 2020 but did not achieve this aim. Senior author of the study, Dr Ingmar Staude, stresses that “Through a comprehensive synthesis of existing national Red Lists with global distribution data, national efforts can be incorporated relatively easily into global risk assessments of plants and, hopefully, accelerate these efforts.” Staude was a doctoral researcher at iDiv and the University of Halle and is now a senior scientist at Leipzig University.