Does the carnauba-palm riverine vegetation constitute a different type of plant community in the Brazilian semiarid? An analysis of the floristic composition

Abstract Floristic surveys are the main source of information about species composition of different vegetation types and a fundamental input of information for biogeographical studies. Within the Caatinga Domain, there are many vegetation types, of which the most conspicuous is the deciduous caatinga s.s. vegetation. However, along the watercourses of this region, one can find a type of riparian forest called Carnaubais, characterized by a larger presence of evergreen species with access to underground water and a conspicuous occurrence of the endemic “carnauba” palm (Copernicia prunifera). The present study aimed at making a floristic survey on a Carnaubal riverine habitat and a nearby caatinga s.s. site in Ceará, and perform a biogeographical comparison with other sites within the Caatinga Domain. In our study site, we identified 186 species, distributed in 135 genera and 52 families. Of the 186 species recorded, we found 123 species uniquely in the caatinga s.s. phytophysiognomy, 40 uniquely in Carnaubal and 23 in both phytophysiognomies. The most representative families were Fabaceae (31 spp.), Poaceae (15 spp.), and Euphorbiaceae (13 spp.). The UPGMA and NMDS analyses supported the idea that the Carnaubal is a habitat with distinct flora within the Caatinga Domain.