Estrutura diamétrica da vegetação arbustivo-arbórea no entorno de nascentes da bacia hidrográfica do rio Piauitinga, Salgado – SE, Brasil

Abstract

This study was carried out in order to analyze the diametric structure of the ciliary vegetation in headwaters in the Piauitinga River drainage basin, located at the town of Salgado, Sergipe, Brazil. One analyzed 14 headwaters, using a classification with regard to the conservation status and the type of reservoir, being divided into 4 categories: 1 punctual preserved (PPr), 1 punctual disturbed (PD), 6 punctual degraded (PD), and 6 diffuse degraded (DD). The survey was conducted through a population census of vegetation in a 50 m radius around the headwaters, equivalent to 0.79 ha, where one recorded all living shrub and tree individuals with diameter at breast height (DBH) ≥ 5.0 cm. The individuals were distributed into diametric classes, at 2.5 cm intervals. The punctual preserved and the punctual disturbed headwaters showed a diametric structure characteristic of heterogeneous forests, with an “inverted J” shape. The diffuse and punctual degraded headwaters didn’t show the “inverted J” pattern, except for DD2, perhaps reflecting the higher number of individuals in this headwater. The intense disturbance generated in the headwater areas, which are currently degraded, promoted the impoverishment of natural regeneration and, as a result, compromised the recruitment of individuals in the early diameter grades.