Trophic facilitation in forest restoration: Can trees use ectomycorrhizal fungi of the pioneer shrub ?

The benefits of plant-to-plant facilitation in ecological restoration are well recognized, yet the potential for indirect trophic facilitation remains understudied. (southern beech; Nothofagaceae) is an iconic southern hemisphere tree genus that is frequently the focus of ecological restoration efforts. One aspect of ecology that may limit restoration success is the availability of appropriate ectomycorrhizal fungi. It has been suggested that pioneer dual-mycorrhizal hosts such as species (Myrtaceae) could facilitate establishment by providing fungal inoculum, but the capacity for to use ectomycorrhizal fungi is unknown. To investigate potential indirect facilitation, we conducted a common garden pot trial to determine if (mountain beech) can use symbionts from (mānuka) ectomycorrhizal communities. and seedlings were grown in monoculture and mixed pairs with reciprocal "home" and "away" soil fungal inoculum. ITS2 metabarcoding of eDNA from hyphal ingrowth bags revealed that and inoculum contained different ectomycorrhizal fungal communities, but that half of the common ectomycorrhizal taxa identified were found in both soil types, suggesting generalist fungi exist. was able to form associations with some fungal species originating from inoculum, however, probable spore contamination meant that the proportion of root colonization associated with those species was ambiguous. Root ectomycorrhizal colonization rates were positively associated with seedling biomass, and there was some evidence of a home soil inoculum advantage in , but these effects were minor. Additionally, we found evidence that home inoculum provides a protective advantage against drought stress for seedlings. Our results indicate the potential for using to promote establishment in restoration plantings and highlight the possible benefits of considering fungal mutualists in ecological restoration projects.