Estudo do componente arbóreo e efeito de borda em fragmentos de Floresta Atlântica na bacia hidrográfica do rio Tapacurá - PE

Abstract

The aim of this study was to evaluate the floristic composition, the successional classification, the phytosociological structure and edge effect on the arboreal component into two fragments of Atlantic Forest in the Watershed of the River Tapacurá - PE. The forest fragments evaluated were Mata da Onça and the Mata da Buchada. For collect of the data from the adult component (CBH 15 cm) were located 15 plots of 10 x 25 m arranged in three rows, each row with five equidistant plots 25 m apart. The first row bordering the edge and the other with 50 m interval, dividing the area into three sectors according to the distance from the edge. Within each plot was implemented a sub-plot of 1 x 25m for survey of the natural regeneration survey (CBH < 15 cm and height 1.0 m). In the Mata da Onça were sampled 851 individuals belonging to 31 botanical families, 48 genera and 77 species. Among these species, 82% were considered typical of Atlantic Forest in early succession. In the structure of the adult component the density was estimated at 1,184 ind.ha-1; the diversity and evenness were 3,61 nats.ind-1 and 0,87, respectively; the diameter distribution in inverted "J" and the hypsometric distribution was observed the greatest number of individuals in the first two classes. In the natural regeneration, the density was estimated at 10,853 ind.ha-1; the values of diversity and evenness were 3.45 nats.ind-1 and 0.88, respectively. In the Mata da Buchada 1,025 individuals were sampled, belonging to 26 families, 33 genera and 60 species.In this area occurs predominantly species of early sucessional, which accounted for 74%. In analyzing the structure of the adult component was found density of 1,680 ind.ha-1; the diversity and evenness were 3.06 nats.ind-1 and 0.79, respectively; 41.1% of individuals sampled are in the first class of diameter distribution and in the hypsometric distribution 45% of individuals showed height > 5 m and 10 m. In the regenerative component there was an estimated density of 10,294 ind.ha-1; the Shannon diversity was of 2.96 nats.ind-1 and the evenness of 0.76. In evaluation of edge effect was found that interactions between the anthropic environment and the fragment cause effects on the arboreal community established surrounding areas, and this effect tends to minimize when away from these areas into the interior of the fragment. These results coincided with those observed in different fragments of Atlantic Forest in Pernambuco, which has identified the current composition and structure of these fragments located in the Watershed of the River Tapacurá, as well as, the edge effect exists. Such information is of paramount importance and should be used in actions to recover and restore forest in the region.