Efeito de borda sobre a estrutura do componente arbóreo em fragmento de floresta urbana, no município de Paulista-PE

Abstract

Many studies show that the edges of the forests typically present different species compositions and community structure when compared to the interior of the forests. However, only a few compare the different edge environment of an even forest fragment. Therefore, understanding how the established populations are affected at these locations is crucial for the conservation and recovery of many fragmented landscapes. Thus, the objective was to analyze the edge effect upon the arboreal structure of the urban forest of Jaguarana, Paulista–PE. The methodology used was in the transect form, at a 10x100 m dimension, subdivided into 10 contiguous parcels of 10x10m. Transects were launched into different edge environments: Environment 1 (A1) –environment at a low level of anthropization, located at a place where there is neither neighborship with communities, nor with roads, when compared to other edge areas, being, in a certain way, more isolated; Environment 2 (A2) –environment at a high level of anthropization, adjacent to Jaguarana Community, suffering greater pressure resulting from the action of humans. Environment 3 (A3) –environment at an average level of anthropization, being located farther from the near forest areas, however, adjacent to the highway BR-101, suffering greater effects related to the abiotic factors. For the analysis, all arboreal individuals with circumference at breast height (CBH) > 15cm, to 1,30m from the ground were collected, totalizing 311 individuals: 129 from A1, 62 from A2 and 120 from A3. Fifty-one taxons were identified: 2 at family-level, 4 at gender-level, 50 at specie-level, and 5 undetermined. The edge environment adjacent to the community differed statistically from the others, according to the T-Test, at 5% of probability, due to its inferiority regarding the number of individuals, although there were no significant differences on the base area among the environments, according to the T-Test, at 5% of probability. The majority of the individuals flocked in the first classes of diameter, tending to the inverted-J, typical uneven-aged forests. The result of the diversity index of Shannon (H’) ranged from 3,16 nats/ind., considered below average of the index found in the fragments of dense rain forests of Low Lands in the state of Pernambuco. The majority of the species presented uniform special distribution and, concerning the ecological groups, the majority were classified at the initial succession stage, at all edge environments.