Phytosociology of clusters of a Deciduous Seasonal Forest in Parque Estadual Quarta Colônia, Agudo-RS

Abstract

The goal of this research was to differentiate the structure and floristic of clusters of the arboreal component of a forest in Parque Estadual Quarta Colônia, Agudo, RS, Brasil. Thirty-three plots of 20 x 20 m were systematically installed for the arboreal stratum sampling (diameter at breast height ? 5.0 cm). The Cluster II showed the highest average diameter (40.0 cm) and the basal area (1.353 m² plot-1= 33.825 m2 ha-1). The highest richness (70 species) and the species diversity (3.60 nats ind. -1) occurred in Cluster I. Different species had the highest importance value in two environments (Cluster I: Nectandra megapotamica = 8.6% and Cupania vernalis = 6.2%; Cluster II: Trichilia claussenii = 13.3% and Allophylus edulis = 6.7%), due to the degree of light dependence. This condition was observed in the horizontal structure of climax shade tolerant species that was further developed in the Cluster II (density = 992.5 individuals ha-1; dominance = 10.384 m2 ha-1; VIR= 42.8%) and pioneers species in the Cluster I (density = 79.5 individuals ha-1; dominance = 0.713 m2 ha-1; VIR= 5.0%). The two clusters showed negative exponential diameter distribution, common to the forests with self-regeneration capacity.