Dispersal of ectomycorrhizal fungi by mammals and its implications for Pinaceae invasion: results from Isla Victoria, Argentina

Toyota Auditorium, Howard H. Baker Jr. Center for Public Policy

Invasive pines in New Zealand and Argentina are not associated with native EM fungi to any great extent, and tend to form symbiosis with non-indigenous fungi. Establishment of Pinaceae in such locations requires the co-introduction of compatible ectomycorrhizal (EM) fungi. Dispersal vectors of compatible ectomycorrhizal fungi from established plantations into native forests include wind and mammals. This project aimed to determine which local mammals can act as vectors of the mycorrhizal fungi on Isla Victoria, Argentina. We used non-indigenous deer and wild boar feces collected on the island to inoculate Pinaceae in a greenhouse experiment. We found that both mammals are dispersing fungi compatible with Pinaceae. Approximately 15 percent of the seedlings growing with deer fecal pellets were colonized and 30 percent of the seedlings growing with wild boar feces were colonized by EM fungi. Rodents are also well known to disperse fungi but observational evidence (by trapping) confirms that rodents are rare in areas adjacent to plantations of non-indigenous trees, so their ecological role seems to be insignificant. Very few fungal species were able to disperse via animal feces, possibly owing to animal preferences and/or the differential ability EM species to germinate after being ingested. The hypogeous genus Rhizopogon was the most abundant genus found. Wild boar, a recent addition to the local fauna, seems to be a key agent dispersing the fungi, so they may contribute to promote the invasions of pine trees. These results show that dispersal of ectomycorrhizal fungi can have an important role controlling the invasion of associated plant species.