Diversity and structure of the lower strata in two successional stages in a subtropical forest, Southern Brazil

ABSTRACT Currently, in Paraná State, forest remnants in advanced successional stages account for less than 1% of its original area. This study compared the understory community across different successional stages of the Araucaria Forest in southern Brazil. Forest remnants, one in intermediate and another in advanced stage of natural regeneration were selected, and a total of 38 plots of 5 × 5 m were sampled. Individuals reaching at least 2 m high or having circumference up to 15 cm at height 1.3 m above the soil surface were measured and identified. In the forest at an intermediate stage, 68 species were recorded being mostly light-dependent, with Nectandra megapotamica as the most important species. On the other hand, at an advanced stage, less species were found (52 species) but most individuals were shade-tolerant, with Rudgea jasminoides as the most important species. These differences are most probably caused because of the canopy density of each fragment. As the comparison with other studies is impaired due to different plot sizes and inclusion criteria, we suggest the standardization to improve knowledge and support biodiversity conservation of the southern tropical forest of Brazil.