Objective   Host selection of ectomycorrhizal fungi (ECMF) in forest soil was studied.

  Method  In the soils at forests of Pinus massoniana (Pm) and Castanopsis carlesii (Cc), various fungi were inoculated into Pm or Castanopsis uraiana (Cu) and designated as treatments of Pm-PmS, Pm-CcS, Cu-PmS, and Cu-CcS. After cultivating the inoculated seedlings for 6 months, mycorrhizal identification on the fungi was performed by ITS. The frequency, infection rate, relative abundance, relative frequency, richness, and diversity of ECMF in the roots of Pm and Cu plants were monitored or calculated. Seedling growth indexes and soil physiochemical properties were determined.

  Result   The Cc forest soil (CcS) showed significantly higher pH and contents of total phosphorus, total carbon, and available phosphorus as well as the seedling shoot dry weight and root length than the Pm counterpart (PmS). The 19 OTUs of ECMF detected in these soil samples belonged to 7 families and 10 genera. Of which, Cenococum geophilum, Rhizopogon boninensis, and Tomentella sp. 2 were commonly found on the two soils. Out of the 13 ECMF identified in PmS, 8 infected Pm and 6, Cu; while among the 9 ECMF identified in CcS, 4 infected Pm and 7, Cu. Both C. geophilum and Sebacina sp. 2 were symbiotic with Pm and Cu. Hyaloscyphaceae sp., Lactarius inconspicuous, Rh. boninensis, Rh. flavidus, Tomentella sp. 1, Tomentella sp. 3 and Tomentellopsis submollis infected Pm, whereas Athelia sp., Amanita sp., L. atrofuscus, Russula minor, Russula sp., Sebacina sp.1, Thelephora sp. 1, Thelephora sp. 2 and Tomentella sp. 4 infected only Cu. The ECMF richness index (IV), Shannon index (H') and Simpson index (D) of PmS were higher than those of CcS. However, the Sorensen index on the PmS planted with host plants other than Pm was 0.14, which was lower than 0.36 on the CcS planted not with Cc. The infection rates of some ECMF were closely related to the physiological and ecological properties of the host.

  Conclusion   The symbiosis between ECMF and trees has evolved in a long process. The ECMF in the soil at a Pm forest tended to infect Pm specifically, and so did those at a Cc forest to Cc, Cu or Fagaceae plants. However, the ECMF in PmS were more selective on their host plants than those in CcS. Even though soil physiochemical properties also affected the ECMF infection, the species of host plant largely determined the fungal colonization on the land.