Patterns of species diversity are essential to understand community structure. We aimed to determine species diversity and patterns of beta diversity in different spatial scales. We sampled three thousand individuals between the coordinates 22°10'S to 22°16'S and 47°47'W to 48°00'W to assess species diversity in three spatial scales (maximum distances of 80 m, 1,400 m, and 12,000 m), using the point-centered-quarter method. We partitioned gamma diversity into alpha and beta components. Beta diversity was partitioned into dissimilarities produced by spatial species turnover and nestedness. The contribution of beta diversity to gamma diversity was greater than that of alpha diversity in all scales, although the patterns of species diversity were similar for the evaluated scales, and was similar to that described for larger spatial scales. The sampled fragments presented means of 15 exclusive species and 47.5 species per fragment, and dissimilarities [β(SØR)=0.7] almost completely explained (94 %) by spatial species turnover. The results indicate that the remnant fragments are residual patches of an originally heterogeneous vegetation. The fragmentation processes could have progressed differently in each portion of the original vegetation, producing the current heterogeneous vegetation. Thus, there is a potential of high local species extinctions if the remnant fragments are deforested.

Este trabalho traz uma revisão de estudos florísticos, relatórios técnicos e relatos de antigos viajantes que cruzaram áreas dos Estados do Piauí e do Maranhão, além de estudos ecológicos e ensaios experimentais envolvendo as palmeiras para compreender o processo de ocupação da região por babaçuais, carnaubais e buritizais, além de outras palmeiras. O objetivo do artigo é entender se a composição fisionômica atual da área foi reflexo da atividade antrópica intensa na região.