Structure of a Semideciduous Seasonal Forest in the National Forest of Ipanema, Brazil: Contributing to the Floristic Knowledge of a Poorly Studied Protected Area

Abstract

Studies on composition and structure generate crucial information for characterizing plant communities and planning conservation actions. There are still substantial knowledge gaps in Brazilian protected areas, preventing design programs to mitigate biodiversity loss. This is the case of the National Forest of Ipanema (Ipanema NAFO) in São Paulo state, Brazil, where plant diversity remains uncalculated. To help fill this gap, in 1-ha of a seasonal semideciduous forest (SSF) stand on the Araçoiaba hill, the authors sampled all woody stems with dbh ≥ 5 cm in a total of 103 dead and 1,301 living plants representing 65 species, 57 genera, and 31 families. The number of species and families was lower than old-growth SSF and, together with the land-use history, which suggests the community is a secondary stand. The initial species Guazuma ulmifolia, Machaerium stipitatum, Croton floribundus, and Aloysia virgata totalized 50% of the living stems, whereas 37% of the other species summed up only 1.8%. The high abundance of these initial species and the presence of the climax species Cariniana legalis, Holocayx balansae, Myroxylon peruiferum, Zanthoxylum caribaeum and others indicate that the community is in an intermediate to advanced successional stage. Three species are considered vulnerable to extinction and 27 of least concern. Ipanema NAFO is an important conservation unit, sheltering some plants vulnerable to extinction and others locally rare. This study adds to other few studies about the flora of Ipanema NAFO, helping to estimate its biodiversity and planning conservation actions. Additionally, it is a source for defining reference values for ecological restoration in the Atlantic forest.