Mycorrhizal fungi colonize of forest floor organic substrates and recycle nutrients directly from these substrates. This recycle pathway is especially important in highly leached, infertile tropical and subtropical soils. However we know little about the diversity and distribution of mycorrhizal fungi in forest floor organic substrates.

We investigated diversity of mycorrhizal fungi associated with decomposing leaves, earthworm’s casts and FH layers in a subtropical forest in southern Japan, using a next generation sequencer.

A total 419,377 ITS1 rDNA sequences were grouped into 2,646 operational taxonomic units (OTUs). One hundred-ten OTUs belonged to taxa containing mycorrhizal species. Common mycorrhizal families were Russulaceae (26 OTUs), Cortinariaceae (25 OTUs), Thelephoraceae (24 OTUs). Russulaceae and Cortinariaceae were more frequent in FH layers, Thelephoraceae and Boletaceae were more in FH layers and casts and Sebacinaceae were more in litters. The difference in associating substrates suggested functional differentiations among mycorrhizal families.