The
Eucalyptus grandis
W. Hill ex Maiden forms symbiotic association with arbuscular and ectomycorrhizal fungi. The porpoise of this work was to evaluate the direct and the indirect population and the diversity of these organisms in this kind forest of in some sandy areas located in the São Francisco de Assis - RS. Soil and roots samples were collected from native field and Eucaliptus cultivation to identify arbuscular mycorrhizal fungi. Sporocarps of ectomycorrhizal fungi were also collected from these areas. The studied areas were characterized as native field and eucalyptus forest with three and eight years old. Results show that the indirect identification (trapping culture) with
Brachiaria brizantha
(A. Rich.) Stapf is efficient in the recovery endomycorrhizal inoculum fungi from the soil. The
Glomus, Gigaspora, Acaulospora and
Scutellospora were the most important genus found. The Acaulospora scrobiculata and Scutellospora heterogama were the predominant species. The ectomycorrhizal fungi found were Pisolithus
sp. Alb. & Schewein; Scleroderma sp. (Persoon) Fries and
Pisolithus microcarpus (Cooke & Massee) Cumm. The relative abundance was predominant with
Scleroderma
sp. The native field showed higher arbuscular mycorrhizal fungi population and diversity in relation to other eucaliptus areas.