Abstract Restinga formations are defined as the vegetation covering sandy coastal sediments deposited during the Quaternary period, regardless their physiognomy. They are usually characterized as areas of confluence between plant species associated with diverse phytogeographical domains. However, detailed floristic and biogeographic studies are still required to better define their distribution patterns, the origins of their plant species, and their biogeographical affinities. In this study, we investigate the floristic similarities among restingas in Northern and Northeastern Brazil and diverse ecosystems from different Brazilian phytogeographical domains (Caatinga, Cerrado, Atlantic Forest and Amazonia). We employed multivariate analyses to investigate differences in species composition and identify floristically similar groups. While sharing species with other ecosystems, restingas exhibit unique floristic composition, representing a coastal flora. Furthermore, the restingas of Northern and Northeastern Brazil are biogeographically subdivided according to previously recognized sectors of the coast of the country. These findings underscore the complex nature of restinga ecosystems, influenced by environmental factors such as geographic distance, geology and climate. These insights contribute to a nuanced understanding of the complex relationships between restingas and their surrounding ecosystems, facilitating informed conservation efforts in the face of escalating urban and industrial expansion along the Brazilian coast. period physiognomy However patterns affinities study Caatinga, Caatinga (Caatinga Cerrado Amazonia. Amazonia . Amazonia) groups flora Furthermore country distance climate

RESUMO Caatinga sensu stricto é a vegetação típica do semiárido brasileiro, adaptada à forte sazonalidade das chuvas e às altas temperaturas. Possui alta riqueza de espécies e alto nível de diversidade beta. O objetivo do estudo foi documentar a flora e fitossociologia das plantas lenhosas e herbáceas de uma área de caatinga. Para isso, amostramos um hectare na Reserva Particular do Patrimônio Natural Fazenda Almas (Estado da Paraíba). A área apresentou diversidade florística de 114 espécies (34 lenhosas/80 herbáceas), semelhante a outros estudos realizados nessa vegetação. O componente lenhoso apresentou densidade absoluta de 4822 ind.ha-1 e área basal de 38,851 m2.ha-1. Para plantas herbáceas foi registrada uma variação na densidade, percentual de cobertura do solo e riqueza de espécies entre as estações seca e chuvosa. Apesar da alta biodiversidade, a caatinga continua passando por extensos processos de degradação ambiental. O presente trabalho documentou a estrutura de um trecho conservado de caatinga que pode ser uma referência para futuros projetos de restauração.

ABSTRACT The caatinga sensu stricto is a typical vegetation type of the Brazilian semiarid region and is adapted to strong seasonality in rainfall and high temperatures. It has a high species richness and a high level of beta diversity. The objective of this study was to document the flora and structure of woody and herbaceous plant assemblages of a site with caatinga vegetation. We sampled one hectare in the Reserva Particular do Patrimônio Natural Fazenda Almas (Paraíba State, Brazil). Our study recorded 114 species (34 woody/80 herbaceous), which is similar to other studies conducted in this vegetation type. The woody component presented density of 4822 ind.ha-1 and a basal area of 38,851 m2.ha-1. For the herbaceous plants, we recorded variation in density, percentage of soil cover, and species richness between the dry and rainy seasons. Despite the high biodiversity, the caatinga still undergoes extensive environmental degradation processes. The present study documented the structure of a conserved tract of caatinga that can be a reference for future restoration projects.