How to best use environmental DNA for fungal red-listing?

For navigating the biodiversity crisis, a major knowledge gap is the conservation status of inconspicuous, but megadiverse and functionally important, soil microorganisms. Massive datasets on soil biota are now accumulating through molecular sampling approaches, but with limited input into practical conservation. We investigated how DNA metabarcoding data of soil fungi contribute to regional Red List assessments that are currently fruit-body based. For nearly 1,500 regionally assessed species represented by ca. 15,000 fruit-body records, each soil sample increased range estimates of threatened and Near Threatened species by 0.18% on average. Even a moderate number of soil samples enabled us to document many previously unrecorded species. Yet, after cumulating >1000 soil samples, about half of the species on regional red list remained undetected. Thus, effective conservation assessment of soil biota requires combining the fruit-body and environmental DNA data, and special efforts to make these usable to conservationists.