More than 150 experts contributed to the report, which the conservancy called the first comprehensive assessment of the extinction threat for all types of trees native to Europe. The European Red List of Trees classified 37% of Europe's 454 native tree species as "threatened." Of those, 15% are "critically endangered," a step away from extinction, the report said..
The findings come amid heightened concern about environmental issues and extinction risks in Europe and beyond. A U.N. report on biodiversity released in May warned that extinction looms for over 1 million species of plants and animals.
IUCN, a 71-year-old organization known for its "Red List" classification of threatened species, said that "invasive and problematic" species are the top threat to European trees, with urban development and "unsustainable logging" as other factors.
The group's Europe director, Luc Bas, said "human-led activities" were resulting in population declines of important tree species. Among the recommendations , the report's authors called for the creation of protected areas, improved monitoring and increased research on the impacts of climate change on forests and individual tree species.
The conservancy highlighted Aesculus hippocastanum, or the horse chestnut tree, native to southeastern Europe. The polished brown conker inside its spiked fruit "is perhaps more famous than the tree itself" because of its use in children's playground games, the report said.
The species, present in Europe since before the last Ice Age, has been threatened by defoliation because of the leaf miner moth, and a blotch caused by a fungus, as well as by human pressures. It is endangered in Bulgaria and Greece and critically endangered in Albania.
This story has been corrected to show the report listed 58% of Europe's 265 endemic tree species as threatened, not the continents 454 native species.