Subterranean community structure of ectomycorrhizal fungi under Suillus grevillei sporocarps in a Larix kaempferi forest.

•  Internal transcribed spacer (ITS) polymorphism analysis for identifying ectomycorrhizal (ECM) fungal species was improved by applying sequencer electrophoresis and terminal restriction fragment length polymorphism (RFLP). •  The improved method employed polymorphism of ITS3-4 region and an ITS terminal-RFLP fragment digested with HinfI. This method enabled each ECM fungal species to be identified with more precision in a mixed-species sample and would accelerate studies on identification of ECM fungal species. •  Up to 30 ECM fungal species were detected in narrow areas under Suillus grevillei sporocarps. Compositions of subterranean ECM fungal species were much more abundant than aboveground ones, and varied from one location to another. Every ECM fungal species was not exclusively dominant over the others, and coexisted with other species. At locations where S. grevillei sporocarps had developed in the previous year, only a few Larix kaempferi root tips developed and were colonized by fewer ECM fungal species. •  Results indicate that the ECM fungal community under S. grevillei sporocarps decayed as a whole within 1 yr after sporocarp formation and was not re-established in the next growing season after sporocarp formation.