We tested the hypothesis that the low tree diversity in a monodominant forest and possible associated environmental factors influenced the ferns occurrence in the Cerrado-Amazon forest transition zone. The objective was to analyse and compare species richness, canopy cover and ecological aspects of ferns in the transitional forests. The ferns were sampled in a Brosimum rubescens Taub. monodominant forest (MO) and a seasonal mixed forest (MI). The terrestrial substrate, hemicryptophytes life form and herbaceous habit were prevalent. The diversity of woody species was higher than that of ferns, which had a total of 304 individuals, seven species, four genera and two families. The richest family was Pteridaceae, represented by five species (71%). MI forest presented six species and Adiantum tetraphyllum Willd. was the principal, with 209 individuals. Only two species were registered in the MO forest, supporting the hypothesis that low tree diversity and associated environmental conditions influences the diversity of ferns. Probably the canopy cover, the quality of the litter layer and/or edaphic factors may be related to the low diversity of ferns in the MO, since such conditions may act as an environmental filter of species, favoring only the most competitive and adapted to such conditions.
canopy cover; filter of species; monodominant forest; light
