Formation of ectomycorrhizae may facilitate early seedling survival of ectomycorrhizal tree species due to enhanced nutrient acquisition. This could be especially important in heavily shaded understories of tropical monodominant forests where host plant photosynthetic capacity is limited. Little information is available on ectomycorrhizal (ECM) fungal colonization or community development of monodominant seedling cohorts, which have high survival rates. Following a 2016 mast seeding event, we sequentially measured percent colonization and species composition of ECM fungi on live and recently dead seedlings of the tropical monodominant tree Dicymbe corymbosa. We also compared seedling ECM fungi to those of nearby adult conspecifics. Ectomycorrhizal fungal communities were remarkably different between seedling age classes, as well as between seedlings and adults. While the /russula-lactarius and /tomentella-thelephora lineages were species-rich throughout, there was 80–90% species turnover between 6- and 12-month-old seedlings. There was no difference in age-class fungal communities across sampling plots, indicating little spatial effect. Fungal colonization extent did not correlate with seedling age or differ markedly between live and dead seedlings. The number of ECM morphotypes increased with seedling age and tended to be greater on live versus dead seedlings. Interspecific competition between ECM fungi or soil nutrient fluxes may influence community assembly of ECM fungi in this tropical monodominant host tree
