Avaliação fitossociológica de um fragmento de caatinga na Bacia Hidrográfica do Açude Jatobá - PB.

Abstract

Phytosociological evaluation of a fragment of caatinga in the Açude Jatobá Watershed - PB. This work was carried out at Fazenda Caroba, municipality of São José do Bonfim-PB, with the objective of evaluating the shrub-tree vegetation of a fragment of caatinga in the hydrographic basin of a Jatobá reservoir. In the floristic and phytosociological survey, 17 plots of 20 x 20 m (400 m²) were used, and the trees were evaluated considering the CAP'S measurement above 6 cm as an inclusion level. A total of 1320 individuals were recorded, belonging to 6 families, 9 genera and 10 species, including the dead group. The three most important families in number of individuals were Apocynaceae with 462, Euphorbiaceae with 387 and Mimosaceae with 291. Based on the diversity indices used, the study area has low diversity when compared to others in the semi-arid region. In the aggregation analysis, the species that showed non-cluster or random distribution was Erythroxylum punges, while Cnidoscolus phyllacabus showed a tendency to cluster, and the others showed a clustered or aggregated distribution. The most important species were Aspidosperma pyrifolium, Mimosa tenuiflora and Croton sonderianus. Aspidosperma pyrifolium was the species that presented the highest density, frequency and dominance. The basal area and total density recorded were 8.84 m² ha"1 and 1941.176 ind ha"1, respectively. In estimating the Diametric Structure, Aspidosperma pyrifolium was present in most diameter classes, followed by the dead group, Mimosa tenuiflora and Croton sonderianus. The species that had basal area represented in most diameter classes were Aspidosperma pyrifolium, dead group, Mimosa tenuiflora, Caesalpinia pyramidalis and Combretum leprosum.