Savannas of the Brazilian semiarid region: what do we learn from floristics?

ABSTRACT

The Cerrado represents the largest extension of savanna in South America. It occupies large stretches of central Brazil, being fragmented towards the Northeast, Southeast, and South regions of the country. Examples of disjunct patches of vegetation with savanna physiognomy within the Caatinga can be found in the Chapada Diamantina, the Chapada do Araripe, in small areas of southern Ceará State, and also in the coastal plains. This study recorded the floristic composition of four savannas within the Caatinga in northern Ceará State and evaluated the floristic relationships between these and other savannas, Cerrado and Caatinga sites. Periodic floristic collections recorded 247 species distributed among 162 genera and 55 families. Fifty-seven percent of the recorded species were of herbaceous or sub-shrubby habit, while the majority of the flora was of the therophytic life-form. Biogeographic analyses revealed that the study sites differ from typical Cerrado in flora and life-form spectra and have closer floristic relationships with Caatinga vegetation. The presence of floristic elements from the Cerrado, together with species from the Caatinga, in the study sites allows us to conclude that these savanna enclaves in the Caatinga are composed of a mixed flora with typical elements of these two Brazilian biomes.

Keywords:
Brazil; Cerrado; floristics; savanna; semiarid; therophytes; vegetation comparisons