Endophytic fungi in living trees - are communities affected more by tree species, tree age, or geographic origin?

Abstract: Endophytic fungi are ubiquitous in living vascular plants and have been identified in most terrestrial environments. The endophytes may have various ecological roles such as commensals, symbionts and latent invaders. Woody plants harbour a diverse array of different endophytic species that have been detected in various habitats, from leaves to roots. However, the knowledge and research about endophytic communities are scarce, especially in relation to conservation of biodiversity. One of the reasons is the difficulties in detecting and identifying the fungal species, which do not form fruitbodies. The project aims to investigate if the species density and species composition differ between tree species (Acer platanoides, Fagus sylvatica, Quercus robur, Tiliacordata), as a function of tree trunk circumference, and among three regions in southern Norway. The analyses were based on a dataset of environmental DNA samples from sapwood of 208 trees. The result show that Q. robur differs significantly from the other tree species in both species density and species composition and hosts considerably more red-listed species. Oak also harboured a substantial portion of species only detected in a single sample. There was no significant difference in species density among the three regions. Trunk circumference affected the fungal endophyte community composition. The results emphasize the importance of oak trees for fungal diversity and red-listed species.