Wild boars as spore dispersal agents of ectomycorrhizal fungi: consequences for community composition at different habitat types

The success of dispersal events depend on the organism's ability to reach and establish in a new habitat. In symbiotic organisms, establishment also depends on the presence of their symbiont partner in the new habitat. For instance, the establishment of obligate ectomycorrhizal (EM) trees outside the forest is largely limited by the presence of EM fungi in soil. Wild boars (Sus scrofa) are important dispersal agents of EM fungal spores, particularly in the moderately dry Mediterranean region. The aim of this study was to explore how EM fungal spores dispersed by wild boars influence the EM fungal community associated with the roots of Pinus halepensis seedlings at different habitat types. Using a greenhouse bioassay, we grew pine seedlings in two soil types: old-field and forest soils mixed with either natural or autoclaved wild boar feces. In both soils, we observed a community dominated by a few EM fungal species. Geopora (85 %) and Suillus (68 %) species dominated the forest and old-field soils, respectively. The addition of natural wild boar feces increased the abundance of Tuber species in both EM fungal communities. However, this effect was more pronounced in pots with old-field soil, leading to a more even community, equally dominated by both Tuber and Suillus species. In forest soil, Geopora maintained dominance, but decreased in abundance (67 %), due to the addition of Tuber species. Our findings indicate that wild boar feces can be an important source for EM inoculum, especially in habitats poor in EM fungi such as old-fields.