O presente estudo teve por objetivo caracterizar o estágio sucessional e as estruturas horizontal e vertical dos estratos adulto e regenerante de um trecho de floresta secundária com Araucaria angustifolia, na Estação Ecológica de Bananal-SP, Brasil. Para amostragem do estrato adulto (CAP > 15 cm), foram alocadas 43 parcelas permanentes de 10 × 20 m. Em cada uma destas, foram aleatoriamente distribuídas cinco subparcelas de 1 × 1 m, para amostragem do componente regenerante (altura > 30 cm e CAP < 15 cm). Considerando-se o componente adulto, a densidade e a dominância foram estimadas em 2.142 ind./ha e 32,49 m²/ha, respectivamente, em valores totais absolutos. Para o componente regenerante, o valor estimado para a Densidade Total absoluta foi de 48.302 ind./ha. A estrutura diamétrica da comunidade segue o padrão J-invertido, o qual não ocorre na população de A. angustifolia; tal condição pode vir a comprometer a manutenção dessa espécie na comunidade.

In the present work, we aimed to evaluate successional forest stage and horizontal, vertical and diametric structures of upper and under strata on a secondary forest stretch under Araucaria angustifolia on the Bananal Ecological Station, São Paulo state, Brazil. During upper stratum survey (circumference at breast height (CBH) > 15 cm), 43 permanent plots of 10 × 20 m were established. In each plot, five sub-plots of 1 × 1 m were randomly allocated for under stratum (total height > 30 cm and CBH <15 cm) survey. Regarding upper stratum, density and dominance were estimated on 2142 ind./ha and 32.49 m²/ha, respectively, in absolute total values. Concerning under stratum, total absolute density was estimated on 48,302 ind./ha. The diametric structure of the community follows the J-invert pattern, which was not observed for Brazilian Pine population, compromising its maintenance in the community. The auto-ecology of the species supports the catalyzation of secondary succession under its crown, which was classified at middle successional stage.

The aim of this work was to evaluate the floristic composition, richness, and diversity of the upper and lower strata of a stretch of mixed rain forest near the city of Itaberá, in southeastern Brazil. We also investigated the differences between this conservation area and other stretches of mixed rain forest in southern and southeastern Brazil, as well as other nearby forest formations, in terms of their floristic relationships. For our survey of the upper stratum (diameter at breast height [DBH] > 15 cm), we established 50 permanent plots of 10 × 20 m. Within each of those plots, we designated five, randomly located, 1 × 1 m subplots, in order to survey the lower stratum (total height > 30 cm and DBH < 15 cm). In the upper stratum, we sampled 1429 trees and shrubs, belonging to 134 species, 93 genera, and 47 families. In the lower stratum, we sampled 758 trees and shrubs, belonging to 93 species, 66 genera, and 39 families. In our floristic and phytosociological surveys, we recorded 177 species, belonging to 106 genera and 52 families. The Shannon Diversity Index was 4.12 and 3.5 for the upper and lower strata, respectively. Cluster analysis indicated that nearby forest formations had the strongest floristic influence on the study area, which was therefore distinct from other mixed rain forests in southern Brazil and in the Serra da Mantiqueira mountain range.