Submitted by Ricardo Cedraz Duque Moliterno (ricardo.moliterno@uefs.br) on 2016-01-20T22:46:00Z No. of bitstreams: 1 GR?NIVEL MOTA DA COSTA (1).pdf: 2200564 bytes, checksum: 3828a984c3a6ee25ef6f2d93f10132ad (MD5) / Made available in DSpace on 2016-01-20T22:46:00Z (GMT). No. of bitstreams: 1 GR?NIVEL MOTA DA COSTA (1).pdf: 2200564 bytes, checksum: 3828a984c3a6ee25ef6f2d93f10132ad (MD5) Previous issue date: 2014-09-24 / The caatinga vegetation of northeastern Brazil mainly occurs in Pre-Cambrian-crystalline-derived soils and sedimentary-basin-derived sandy soils. Recent evidence has shown variations in the dynamics, structure and floristic composition of the caatinga, which justifies the need for studies focusing on different substrates. A floristic study of the caatinga ecoregions Depress?o Sertaneja Meridional and Raso da Catarina in the municipality of Tucano, Bahia, Brazil, is of special interest because both substrates occur in a local scale, letting the opportunity to broaden our knowledge on ecological heterogeneity within the Caatinga biome. In the current study we carried out a floristic survey of 14 sites distributed throughout the ecoregions of caatinga in Tucano. We found high species diversity in the caatingas of Tucano when compared to other areas in northeastern Brazil. A total of 451 species, 288 genera, and 82 families were collected. The most species rich families are Leguminosae and Euphorbiaceae. There occur 226 species in the sites on crystalline basement, whereas 284 species were collected in the sandy areas. The ecoregions were only 13% similar in floristic composition. We found strong differences between the ecoregions with respect to floristic composition and predominant plant habit as proxy for phytophysiognomy. Overall, our results reinforce the hypothesis of two distinct biotas that assembly the caatinga dry woodlands. / A vegeta??o de caatinga do nordeste brasileiro ocorre principalmente sobre solos derivados de rochas cristalinas pr?-cambrianas e sobre cobertura arenosa de bacias sedimentares. Evid?ncias recentes t?m demonstrado varia??es na din?mica, estrutura e composi??o flor?stica da caatinga, o que fundamenta a necessidade de estudos com enfoque nos diferentes substratos. O presente estudo flor?stico das ecorregi?es de caatinga, Depress?o Sertaneja Meridional e Raso da Catarina, no munic?pio de Tucano, Bahia, ? de especial interesse porque h? esses dois substratos em escala geogr?fica local, permitindo ampliar o conhecimento sobre a heterogeneidade do Dom?nio da Caatinga. Neste trabalho ? apresentado um invent?rio flor?stico de 14 localidades nas duas ecorregi?es de caatinga. Em conjunto, as caatingas amostradas apresentaram uma alta riqueza flor?stica em compara??o com outras ?reas no nordeste do Brasil. Foram coletadas 451 esp?cies, 288 g?neros e 82 fam?lias. A maior riqueza em esp?cies foi das Leguminosae, seguida por Euphorbiaceae. Nas localidades sobre substrato derivado do embasamento cristalino ocorreram 226 esp?cies, enquanto nas de substrato arenoso ocorreram 284 esp?cies. A propor??o de esp?cies em comum nas duas ecorregi?es foi apenas 13%. Diferen?as em composi??o flor?stica refor?am a hip?tese de duas biotas distintas associadas aos dois principais tipos de substrato, que comp?em a vegeta??o da caatinga.