This study aimed to determine the floristic groups, the discrimination and the evaluation of important species in the floristic composition in two research areas located on the National Forest of Irati, Paraná State, Brazil. An area of 10 ha was installed in a Araucaria stand deployed 60 years ago (area A), where arboreal species were established, while another 25 ha area was installed in a Mixed Ombrophylous Forest (area B). The areas were set up from continuous blocks of 1 ha (100 m x 100 m) divided into plots of 0.25 ha (50 m x 50 m), where all trees with diameter at breast height (dbh) equal or higher than 10 cm were measured and identified. We used statistical multivariate techniques, cluster, and discriminant analysis, in order to identify the floristic groups formation in these areas and the species of discriminant groups. An array containing the data was structured containing the coverage value of the i-th plot obtained from the j-th species. Six groups were identified by cluster analysis. The first and the second group gathered 15 and 24 parcels, respectively, belonging to the area A. In the 25 ha from the area B, four groups (3, 4, 5, and 6) were obtained, gathering 28, 21, 36, and 16 plots. With discriminant analysis, we obtained 12 variables (species) that could differentiate the formed groups. Carrying out the groups' phytosociological analysis, the following associations were identified: "association with Araucaria angustifolia stand I; association with Araucaria angustifolia stand II; Nectandra grandiflora association; Ocotea porosa association; Ocotea odorifera association; Matayba elaeagnoides association.
Multivariate analysis; Floristic composition; Phytosociology
