Samambaias e licófitas da Floresta Atlântica Nordestina: Gradiente latitudinal, aspectos ambientais e distância geográfica

Abstract

The Atlantic Forest is one of the most important "hotspot" for conservation in the world, however the north of this forest have more fragmented and less studied portion. Due to lower species richness that ferns and Lycophytes have, compared with the angiosperms, and also its restriction on microhabitats, these groups has been receiving more attention in ecological studies, given the relative practicality to inventory. Thus, we analyze how some variables can influence the floristic richness and composition of these groups in 30 sample units. We applied a multiple regression, an ordinance (CAP) and the Mantel test to see how the factors are influencing the richness and species composition. We find that the richness of these groups had a significant relationship with the latitudinal gradient, tending to increased towards the lower latitudes and in places with fewer dry months and elevated localities. Separately the richness ferns also increased with the lowest levels of the average number of dry months and historical average rainfall. Already the lycophytes had their richness related to lower levels of vegetation. The composition of the sites shown to be influenced by the geographical distance, altitude, longitude and medium and minimum length of the dry months. Thus, our study emphasizes the deterministic aspects of the richness and composition species of ferns and Lycophytes in the Northeastern Atlantic Forest.