Riqueza, diversidade e composição florística em áreas de cerrado em regeneração e preservado na estação ecológica de Itirapina - SP

Abstract

The capacity of 'cerrado' species to regrow from underground organs after deforestation depends on the soil physical and chemical properties and the time elapsed since the disturbance. In Itirapina Ecological Station, we carried out floristic and phytosociological surveys of both herbaceous and woody components of the vegetation in 'cerrado' in a regenerating plot, after two years of Pinus elliotti removal, and in a neighboring preserved the 'cerrado' area. In each of the two areas have been launched along a transection, 20 parts of 5 m x 5 m, systematically distributed to each 20 m. These plots were sampled the woody component (all woody plants with stem diameter at ground level equal to or greater than 3 cm). In each of the plots was defined a sub-portion of 0.5 m x 0.5 m, which was sampled at the herbaceous component (all woody plants with a stem diameter at the ground level lower than 3 cm and all non-woody). The lowest diversity index was found for the herbaceous component of the regeneration area (1.29 nats.individual-1), while the highest was for the herbaceous component of the preserved area of 'cerrado' (2.75 nats. individual-1). Among the areas being regenerated and preserved, Sørensen's similarity indices for both the herbaceous component (0.23) and for the woody component (0.31), showed low floristic similarity between areas. Besides, the density and richness for both components were significantly higher for the area preserved in 'cerrado'. The results showed that the two years elapsed since Pinus elliotti clear-cut were not enough for the natural vegetation recovery.