Summary• To advance our understanding of host effects on the community structure of ectomycorrhizal fungi (EMF), EMF communities were compared among different host species, genera and families in two mixed conifer-broadleaf forests in Japan.• Using molecular identification methods we examined EMF root tips of eight coexisting species belonging to six genera (three families): Abies and Tsuga (Pinaceae), Betula and Carpinus (Betulaceae) and Fagus and Quercus (Fagaceae).• In total, 205 EMF species were detected, and the total richness was estimated to exceed 300 species using major estimators. Of the 55 EMF species occurring three or more times, eight showed significantly biased host preference. A Mantel test showed a significantly negative correlation between EMF community similarity and host taxonomic distance. Detrended correspondence analysis separated EMF communities mainly by host taxonomic and successional status.• Thus, EMF communities are similar on hosts with similar taxonomic and successional status. A significant proportion of EMF exhibited host specificity, which may contribute to the extremely diverse EMF community in conifer-broadleaf forests.

SummaryGeographic and taxonomic host ranges determine the distribution of biotrophic organisms. Host phylogenetic distance strongly affects the community composition of pathogens and parasites, but little is known about the host phylogeny effect on communities of mutualists, such as plant-pollinator and plant-mycorrhizal fungi systems.By incorporating phylogenetic eigenvectors into univariate and multivariate models, we aimed to determine the relative contribution of host phylogeny and environmental variables to mycorrhizal traits and community composition of ectomycorrhizal (EcM) fungi in Salicaceae at the local scale.Host phylogeny explained 75% of the variation in fungal species richness and 20% of the variation in community composition. We also re-analyzed a system involving eight hosts from Japan, in which host phylogeny explained 26% and 9% of the variation in fungal richness and community composition, respectively. [Correction added after online publication 21 May 2013: in the preceding sentence the values 9% and 26% have been transposed.]Phylogenetic eigenvectors that differentially account for clades and terminal taxa across the phylogeny revealed stronger host effects than did the treatment of host species as categorical or dummy variables in multiregression models, and in comparison with methods such as Mantel test and its analogs. Our results indicate the usefulness of the eigenvector method for the quantification of the host phylogeny effect, which represents an integrated complex function of taxonomic sampling effect and phylogenetic distance per se.

Summary• The spores of ectomycorrhizal fungi (EMF) play critical roles in the population and community development of EMF. Here, the germination and infectivity of EMF spores are examined with reference to the ecological traits of the EMF species.• Spores were collected from 12 EMF species, whose successional patterns have been studied in the volcanic desert on Mount Fuji, Japan. Spore germination experiments were conducted with host plants (Salix reinii), with nonhost plants (Polygonum cuspidatum), and without plants. The mycorrhizal formation ability of spores was also examined in seven EMF using spore inoculation experiments. To determine the effects of the spore preservation period, both experiments were repeated up to 1 yr after spore collection.• Spore germination was very low in the absence of host plants. In the presence of hosts, even 30 d after spore collection, spore germination was significantly enhanced in all pioneer EMF (c. 20%) but less so in late-stage EMF (< 5%), except in Hebeloma species. Mycorrhizal formation from spores was also greater in pioneer EMF but was significantly reduced by 1 yr of spore preservation.• High spore germination and infectivity of pioneer EMF should enable these species to colonize disturbed and isolated areas in accordance with their ecological traits.