Abstract
Southern beech (Nothofagus, Nothofagaceae) trees are an iconic Southern Hemisphere canopy species and are of particular interest for restoration in New Zealand. One poorly understood aspect of beech ecology that can limit restoration success is the role symbiotic fungi play in seedling growth and survival. It is possible that beech establishment could be facilitated by the dual-mycorrhizal (ectomycorrhizal (ECM) and arbuscular mycorrhizal (AM)) pioneer species mānuka (Leptospermum scoparium, Myrtaceae), due to shared ECM fungal symbionts. To investigate this proposed facilitation, I conducted a common garden pot trial using soil inoculation bioassays to determine the capacity for mountain beech (Nothofagus solandri var. cliffortioides) to utilize symbionts from mānuka mycorrhizal communities. I assessed the effects of soil inoculum source and associated mycorrhizal communities that were identified using DNA barcoding on the survival and growth of mountain beech and mānuka seedlings. Metabarcoding results revealed that beech and mānuka soil inoculum sources provided different ECM fungal communities. However, ECM root colonization on beech was high when grown in both mānuka and beech soil, indicating that beech seedlings are able to form mycorrhizal connections with mānuka inoculum. Root colonization had a significant positive relationship with seedling biomass. Beech biomass was slightly lower when inoculated with mānuka soil compared to other inoculation mixtures. Thus, mānuka fungal communities may be slightly suboptimal for beech seedling growth, but can provide effective ECM associations, which supports using mānuka as a facilitator for beech seedling establishment. Additionally, results from this study indicate that mycorrhizal fungi may play an important role in mānuka seedling survival when subjected to drought stress, however, there was no significant effect on beech seedling survival. These findings should have practical implications for future restoration strategies in New Zealand.