Estrutura horizontal da comunidade arbórea sob um povoamento com Araucaria angustifolia e uma Floresta Ombrófila Mista

摘要

The horizontal structure of the arboreal community under an Araucaria angustifolia stand with 60 years and a Mixed Ombrophyllous Forest in National Forest of Irati, Parana State - Brazil, were compared. In both areas were established permanent plots of 1 ha (100 m x 100 m): 10 plots (10 ha) in the A. angustifolia stand and 25 plots (25 ha) in the natural forest. All of the individuals with dbh above 10 centimeters were identified, numbered and positioned spatiality. The phytosociological parameters and diametric distribution of the two communities were determined and related. In the stand, the species with highest importance and coverage values, when not considering the Araucaria angustifolia trees remnants in plantation were Myrsine umbellata, Psychotria Vellosiana, Cabralea canjerana, Casearia sylvestris, Alchornea triplinervia and Cedrela fissilis, while in the forest were Araucaria angustifolia, Ilex paraguariensis, Ocotea odorifera and Nectandra grandiflora. The Kolmogorov-Smirnov test indicated that stand plots were different from the forest in terms of diametric distribuition, besides presenting the lowest variation. In general, the stand species are ahead in an initial successional stage and has limitations for their development. This fact is likely related with the high planting coverage (basal area = 30.2 m² ha-1). doi: 10.4336/2010.pfb.30.64.347