Species richness in restinga vegetation on the eastern Maranhão State, Northeastern Brazil

ABSTRACT The State of Maranhão comprises the second largest coastline in Brazil. Nonetheless, few floristic surveys on restinga vegetation have been performed in Northeastern Brazil. This study aimed to survey floristic in a restinga of Maranhão, and to assess its similarity to other restingas in the states of Pará and Piauí. Botanical specimens were sampled at Sítio Aguahy, in the municipality of São José de Ribamar, along the eastern coast of Maranhão between June/2012 and October/2013. Species identification and life forms classification followed the usual methods employed in floristic studies. Similarities in plant composition of six sites were estimated based on cluster analysis through Bray-Curtis distance. In the studied area, we found 116 phanerogamic species, 100 genera and 52 families; 19 species were new occurrences for the restinga of Maranhão. Families with largest number of species were Fabaceae, Cyperaceae, Rubiaceae, Poaceae, Myrtaceae, Asteraceae, Malvaceae, Combretaceae, and Eriocaulaceae, which comprised 49.2% of all sampled species. We identified 41 nanophanerophytes, 34 terophytes, 15 camephytes, ten microphanerophytes, six hemicryptophytes, and five lianas. Similarity analyses indicated greater affinity between the restinga flora from the states of Maranhão and Pará than that observed for the states of Maranhão and Piauí, suggesting that the process of species colonization in the former is more likely derived from the Amazon Forest. It is expected that these results may encourage future researchers to conduct further surveys in restinga areas of the Maranhão aiming to better understand the influence of neighboring vegetation on the colonization of the coastal areas of Maranhão.