The vegetation of the Brazilian restinga (coastal woodland) presents a variety of species and different characteristics, encompassing fields, fruit groves and forests on quartzarenic neosols. We hypothesised that the structure of the restinga landscape along the coast of the state of Piauí is influenced by edaphic factors and presents a pattern similar to that of other northeastern restingas. We evaluated three restingas in Piauí, using the quarter method to determine their structure. Composite soil samples were collected to determine their chemical and physical properties. Edaphic variables were correlated with plant species by canonical correspondence analysis (CCA). Phytosociological data for all three areas indicated regenerating vegetation comprising several small individuals, 82.5% of which showed a diameter at ground level < 13 cm. We also observed considerable tillering. In two of the areas, there was a predominance of Fabaceae species, such as Caesalpinia pyramidalis and Copaifera martii. Although the structural characteristics of the restingas studied were similar to those of other northeastern restingas, the former showed lower Shannon diversity indices (2.18-2.44). The CCA indicated that species distribution was influenced by edaphic factors such as pH, aluminium content and amount of organic matter. The restingas studied were similar to others along the Brazilian coast.
canonical correspondence analysis; coastal vegetation; edaphic interactions
