The floristic and phytosociological studies contribute significantly to the knowledge of forest formations by showing the richness and diversity of the environments evaluated. This work was performed in a hypoxerophytic Caatinga fragment in the city of Arcoverde, Pernambuco state and aimed at determining the floristic composition and phytosociological parameters of tree and shrub species that make up the fragment. The study was conducted in 40 plots (10 x 25 m) with inclusion level the circumference at 1.3 m above the ground with CAP > 10 cm. The absolute and relative density, absolute and relative frequency, absolute and relative dominance and importance value were evaluated; species diversity was given by index of Shannon-Weaver (H') and equality of Pielou evenness, determining the hypsometric distribution at one meter intervals and diameter distribution at 3 cm intervals. In the floristic survey of adults, 1,491 individuals were found alive, distributed in 36 woody tree and shrub species, 19 families and 31 genera. Families that stood out most were Mimosaceae, Euphorbiaceae, Anacardiaceae, Caesalpiniaceae and Rhamnaceae. The diversity index of Shannon-Weaver was 2.05 nats/ind. and equality of Pielou evenness was 0.57. For the seven phytosociological parameters evaluated, the species that stood out were Mimosa ophthalmocentra, Poincianella pyramidalis, Senegalia bahiensis, Senegalia paniculata, Croton blanchetianus and Mimosa tenuiflora, indicating that these are the species best adapted to the environment assessed, both in environmental conditions and competition with other species present in the fragment of Caatinga in Arcoverde-PE.
Diversity; Frament; Structure
