"Rädda Asken": A scientific perspective on Sweden's efforts to conserve Ash Fraxinus excelsior since 2013

Since ash dieback was reported in Sweden in 2001, the invasive fungus Hymenoscyphus fraxineus has caused mortality of Fraxinus excelsior, threatening biodiversity, ecosystem functions, landscapes, and hundreds of associated species. This perspective reviews more than a decade of conservation efforts led by Rädda Asken ("Save the Ash"), a citizen science initiative launched in 2013 without dedicated state funding. Public engagement identified nearly 1300 putatively resistant trees, enabled clonal propagation, and established conservation and breeding infrastructure. Research showing that resistance is heritable supports breeding and restoration. However, fragmented financing and limited national coordination have restricted progress. Key uncertainties concern the durability of resistance, maintenance of genetic diversity, secondary pathogens, and the threat of Agrilus planipennis. Sweden's experience demonstrates both the value and limitations of grassroots conservation efforts. Future recovery of ash and its associated biodiversity will require sustained investment in breeding and research, in addition to a coordinated, long-term restoration programme that supports implementation, monitoring and adaptive management.