This study investigated the floristic composition and the tree community structure in a secondary Araucaria
Forest fragment in the Southern Plateau Region of Santa Catarina state, Brazil, the floristic context of
this fragment in relation to other areas of Araucaria Forest in the region and the influence of climatic and geographic variables on the clustering patterns observed. The phytosociological survey of tree vegetation
was assessed through 25, 400 m
2, plots, where all trees with DBH (diameter at breast height) ≥ 5 cm
were measured and identified.The floristic relationship among remnants and the influence of climatic and
geographic variables were analized through a Multivariate Regression Tree, using a presence-absence species
matrix and a climatic-geographic variables matrix. In the study area, 87 species were found, distributed into
36 botanic families. The species with the highest importance value were
Araucaria angustifolia
(Bertol.)
Kuntze and
Podocarpus lambertii
Klotzsch. While the distribution of individuals in diametric classes was
similar to an inverted J shape for the community, the populations demonstrated different shapes of diametric
distribution. In the region, three floristic clusters were discriminated, influenced mainly by temperature
seasonality and annual mean temperature. The study site was grouped with together with other areas
presenting temperature seasonality higher or equal to 3.053°C.