Resumo. ABSTRACTThe majority of the Conservation Units (CUs) of Curitiba (Paraná state, Brazil) are plagued by invasivealien tree species (IATs). However, no studies have been carried out to evaluate their impact or to determinethe appropriate management techniques. The objective of this study is to evaluate the participation of IATsand the implications and management of the most significant species causing major structural change inthe floristic-structural composition of ‘Barreirinha’ Park, a remnant of Araucaria Forest. Four plots wereevaluated in a total area of 1600 m² representing approximately 4% of the total area of the forest. A total of354 individual trees were sampled with a diameter of ≥ 15 cm, and for each species sampled, parameterswere calculated of the relative frequency, relative density, relative dominance and the importance value. Itwas possible to identify 29 families, 43 genera and 57 species, three of which were IATs. The sustainabilityand integrity of this Conservation Unit can be threatened by the presence ofPittosporum undulatum(SweetPittosporum), the species with the greatest structural importance value, high density and frequency. Possiblemanagement strategies for thePittosporum undulatumspecies are presented.