Share This An estimated 31% of the world’s oak species are threatened with extinction according to data compiled in a new report by The Morton Arboretum and the International Union for Conservation of Nature (IUCN) Global Tree Specialist Group, The Red List of Oaks 2020. An estimated 31% of the world’s oak species are threatened with extinction according to data compiled in a new report by The Morton Arboretum and the International Union for Conservation of Nature (IUCN) Global Tree Specialist Group, The Red List of Oaks 2020. The report details for the first time the distributions, population trends and threats facing the world’s estimated 430 oak species, and will serve as a roadmap for conservation action.