Implications of reserve size and forest connectivity for the conservation of wood-inhabiting fungi in Europe

Among the factors that affect the conservation efficiency of protected areas, lack of connectivity is considered as one of the main problems. In this study, we assessed the influence of connectivity of European beech forest reserves on wood-inhabiting fungal communities, compared to the influence of local factors. To address this topic,we used a data matrix consisting of 344 fungal species on 1571 resource units (i.e. fallen beech logs, including their standing snags) sampled in 42 European beech forest reserves. Our results show that connectivity has significant effects onwood-inhabiting fungal communities in European beech forest reserves, and that the effectiveness of reserves for maintaining the wood-inhabiting fungal diversity is compromised by habitat fragmentation. Connectivity at small scales (measured as the area of the reserve) had a strong influence on the occurrence of indicator species and was also critical for the number of species at a resource. Connectivity at larger scales (connectivity to surrounding beech forests) seemed to be particularly critical for the community composition both at resource and reserve levels. In line with previous research, we found other covariates such as size of the resource units and annual temperature range to positively influencewood-inhabiting fungal species richness. The effects of habitat fragmentationwere especially strong in western and northern European regions where the smallest and more isolated reserves were located. We propose that an effective conservation strategy for woodinhabiting fungi should focus on increasing the areas of the present reserves as well as conserving newreserves in the proximity of the existing ones.