City life of mycorrhizal and wood-inhabiting macrofungi: Importance of urban areas for maintaining fungal biodiversity

The biodiversity of mycorrhizal and wood-inhabiting macrofungi (basidiomycetes) is declining, and many species are threatened in forests. Based on data from a 30-year fruiting body survey from 1988 to 2017 in the region of the city of Jena (100,000 inhabitants, 4500 ha forest), Germany, we evaluated the role of the urban environment with a variation of ownership, property size, associated management, and high diversity of woody species for the presence of non-red list and red-list fungal species. We found that (i) the urban area hosted 1172 mycorrhizal and wood-inhabiting basidiomycete macrofungi, identified on 64 woody host genera, representing 23% of the total German basidiomycetes on 0.4‰ of the German forest area. Among these species, 194 species (16%) are threatened according to the German Red List; (ii) a few common forest tree genera (Fagaceae and Pinaceae) hosted 90% of the total and red-list fungal species detected in this study; (iii) plant identity and host functional groups rather than plant phylogeny shaped the community composition and richness of mycorrhizal and wood-inhabiting macrofungi; (iv) conifers contributed 66% and 51% and broad-leaved trees 80% and 74% to total and red-list fungal diversity, respectively; (v) red-list species occurred mainly on common forest trees and shrubs from Fagaceae, Pinaceae, Betulaceae, Salicaceae, and Oleaceae, especially on native ones; and (vi) a few exotic trees (Robinia pseudoacacia and Pseudotsuga menziesii) supported a diverse native fungal flora. We conclude that urban areas can serve as an important zone for maintaining mycorrhizal and wood-inhabiting macrofungi by promoting a high heterogeneity of land use, ownership, and a high diversity of woody species.