Variações locais na riqueza florística em duas ecorregiões de caatinga

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.

Flora and physiognomy of Caatinga vegetation over crystalline bedrock in the northern Caatinga domain, Brazil

Abstract The Seasonally Dry Tropical Forests and Woodlands biome (SDTFW) has its largest nucleus in the Caatinga domain. We characterized the flora and physiognomy of the vegetation in the Pedra da Andorinha Wildlife Refuge (RPA), in Ceará, Brazil. Plant collections were made between March/2015 and May/2021, applying usual botanical methods. All material was deposited in HUVA herbarium. The phytosociological studies covered five 50 m x 50 m plots established (1.25 ha) in which all individuals with diameters at soil level ³ 3 cm were inventoried. We identified 266 vascular plants species distributed among 185 genera and 67 families, including one fern (Marsilea deflexa - Marsileaceae). Fabaceae had the greatest species richness (38 spp.), while Ipomoea was the richest genus (9 spp.). 43.6% of all plant species were herbaceous, with a predominance of therophytes (57.5% of all herbaceous plants). The phytosociological study sampled 1,988 individuals distributed among 24 species of 13 families. The species with the greatest important value were Cordia oncocalyx (Boraginaceae) and Croton blanchetianus (Euphorbiaceae). We classify the local physiognomy as typical caatinga sensu stricto vegetation and rocky vegetation on inselbergs and outcrops. We highlight the richness of herbaceous plants in the local community, which surpass the richness of the woody component.