Stand structure and deadwood amount influences saproxylic fungal biodiversity in Mediterranean mountain unmanaged forests

Old-growth forests are key elements of ecosystem diversity and conservationstrategies, providing niche differentiation and trophic pathways that producestructural and compositional heterogeneity. In these forests, deadwood is particularlyimportant for saproxylic and mycorrhizal fungi, sustaining forest productivityand environmental services. In this study, the saproxylic fungaldiversity in Mediterranean mountain forests, characterized by different managementhistories and forest types (holm oak and beech), was analyzed. Therelationships between saproxylic fungal biodiversity and structural attributeswere considered in three forest stands of the Apennines (Italy). In addition,descriptive environmental parameters and forest traits were related to prevailingfungal communities, in order to analyze the species composition anddistribution patterns of saproxylic fungi resulting from the ordination processes.The study sites were selected on the basis of their late-serial stage ofdevelopment. Species frequency was analyzed through multivariate techniquesto test the relationships between fungi, structural attributes and environmentalvariables. A Detrended Correspondence Analysis (DCA) was used toinvestigate the response of the overall fungal community structure to environmentalgradients. Living tree volume, altitude, vegetation type, and the frequencyof species with ephemeral sporocarp lifespan played a crucial role indiversifying species distribution patterns. Deadwood volume and decay classeswere related to taxonomic and trophic community diversity. However, differencesbetween the considered climatic regions exerted a major role on theoccurrence of fungi with ephemeral sporocarps more than deadwood abundance,utilized primarily as fructification substrate.