Floristics and life-forms along a topographic gradient, central-western Ceará, Brazil

• Autor(a) principal: Araújo,Francisca Soares de
• Data de Publicação: 2011
• Outros Autores: Costa,Rafael Carvalho da, Lima,Jacira Rabelo, Vasconcelos,Sandra Freitas de, Girão,Luciana Coe, Souza Sobrinho,Melissa, Bruno,Morgana Maria Arcanjo, Souza,Sarah Sued Gomes de, Nunes,Edson Paula, Figueiredo,Maria Angélica, Lima-Verde,Luiz Wilson, Loiola,Maria Iracema Bezerra
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Rodriguésia (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S2175-78602011000200341
• topic: vegetation classification; biological spectrum; growth-form; phytoclimate; plant community

Abstract To test whether the flora is organized in discrete or continuous units along a topographic gradient, three physiognomies were assessed on different soil classes in a semi-arid region of northeastern Brazil: caatinga (xeric shrubland) at altitudes from 300 to 500 m, deciduous forest at altitudes from 500 to 700 m and carrasco (deciduous shrubland) at 700 m. In each physiognomy a species inventory was carried out, and plants were classified according to life- and growth-forms. Species richness was higher in the deciduous forest (250) than in the carrasco (136) and caatinga (137). The caatinga shared only a few species with the carrasco (6 species) and the deciduous forest (18 species). The highest species overlap was between the deciduous forest and the carrasco (62 species). One hundred and four species occurred only in the caatinga, 161 only in the deciduous forest and 59 only in the carrasco. Woody species predominated in physiognomies on sedimentary soils with latosol and arenosol: 124 species occurred in the deciduous forest and 68 in the carrasco. In the caatinga on crystalline basement relief with predominance of planosol, herbs showed the highest species richness (69). Comparing the biological spectrum of Brazilian plant life-forms, the caatinga stood out with higher proportion of therophytes and chamaephytes. Considering the flora of the three phytophysiognomies studied here, we can affirm that the caatinga is a discrete floristic unit.