From August/1984 to May/1987, 300 soil samples were collected from the rhizospheres of 35 species of native plants of Parque Estadual da Ilha do Cardoso, SP, Brazil, in a wet tropical forest, to investigate the occurrence and some ecological aspects of vesicular-arbuscular mycorrhizal (VAM ) fungi. Thirty five taxa of VA M fungi were reported, seven of them as new species. The most numerous VA M fungal spores belong to Acaulospora foveata Trappe & Janos, Acaulospora scrobiculata Trappe. Glomus etunicatum Becker & Gerd., Glomus geosporum (Nicol. & Gerd.) Walker, Glomus macrocarpum Tul. & Tul. and Glomus microcarpum Tul. & Tul. The rhizospheres that presented the highest number of VA M fungi spores were Blechnum serrulatum L.C. Rich., Euterpe edulis Mart., Neomarica caerulia Sprague and Piper aduncum L. The highest diversity of VA M fungi species occurred in the rhizospheres of Aphellandra sp., Geonoma elegans Mart, and Leandra barbinervis Cogn. It was observed that clamydosporic species of vesicular-arbuscular mycorrhizal fungi were more numerous than azygosporic species; the number of spores is correlated with the diversity in a rhizosphere. Glomus monosporum Gerd. & Trappe and Sclerocystis species are characteristic of the studied ecosystem, that presented the average of 50,04 spores/100g of soil.
VAM fungal ecology; wet tropical forest; Brazil