Influence of palm trees on the richness and distribution of plant species on the murundus at a Caatinga/Cerrado ecotone

Understand the role of the drivers in vegetation pattern is essential in ecology since diversity plays a major role in the stability and maintenance of plant communities. The murundus are small and scattered earthmounds with a differentiated flora of its surrounding. In our study site (Campo Maior, Piaui, Northeastern Brazil), we classified them in three categories: presence of carnauba (PC), presence of tucum (PT), and with the absence of palm trees (AP). Here, our goals were (1) to explore alpha diversity using the richness estimator and abundance distribution rank, expecting that palm trees could influence the richness of plant species on murundus; (2) analyzing the species richness-area relationship in the murundus, following the assumptions that the largest one holds more species; (3) find the changes in the species composition (beta diversity) between the three categories of murundus, assuming which the presence of palm trees influence the species composition; and (4) investigate if the distance between murundus is a decisive factor in the species composition, where the closest murundus are the most similar in species composition. Ours results showed that palms trees do not influence the richness of the murundus, the largest murundus are the richest ones, and the turnover predominantly determines beta diversity in the different murundus categories. Furthermore, the distance between the murundus did not determine its floristic similarity. Overall, we demonstrated which the species of palm trees are not the main drive of the plant assemblage in the murundus, however its size comprises a major factor in the richness, with great species substitution, which explains the high plant diversity.