Data from: Host plant phylogeny and abundance predict root-associated fungal community composition and diversity of mutualists and pathogens

• Interactions between plants and their root-associated fungi (RAF) may
influence the relative abundance of tree species and determine forest
community diversity. Such plant-soil feedbacks in turn depend on the
degree to which spatial distance and phylogenetic relatedness of host
trees structure pathogen and mutualist communities, but research detailing
these aspects of RAF communities is lacking. Here, we characterize
plant-RAF associations across a diverse plant community, focusing on the
degree to which RAF communities are structured by spatial distance, host
phylogenetic relatedness, and host abundance. We compare results for
different functional groups, including both putative mutualists and
pathogens, an aspect poorly examined hitherto. • We collected roots at
regular intervals along ten 50 m by 2 m transects, then used DNA barcoding
to identify host plants, and characterize the associated fungal community.
Variance partitioning was used to measure the relative contributions of
host phylogenetic relatedness and spatial distance to explaining RAF
community composition. A weighted linear regression was used to measure
the correlation between host abundance and RAF diversity. • Phylogenetic
distance among hosts was a better predictor of RAF community composition
than spatial distance, but this relationship was stronger for putative
pathogens than for mutualists, suggesting that pathogens show stronger
host preference than mutualists. Across all functional groups, RAF showed
similar levels of spatial structure. Additionally, RAF communities of
locally abundant plants were less diverse than RAF communities of rare
plants. • Synthesis: We found that RAF communities are structured by the
phylogenetic relatedness of hosts and, to a lesser extent, by spatial
distance, with pathogens showing stronger host preference than mutualists.
Abundant hosts had less diverse RAF communities than rare hosts, which is
notable because abundant plants tend to experience weaker negative
plant-soil feedback. Going forward, mechanisms underlying the host
abundance-RAF diversity relationship warrant further investigation.
Additionally, the survey approach presented here could be paired with
experiments linking RAF community composition to plant recruitment.