In the current context of intense forest fragmentation and consequent loss of biodiversity, commercial reforestations have gained special attention in conservation biology because the colonization of the understory in these wooded areas may result in a considerable number of species. A record was made of the regenerating species in the understory of reforestations with Araucaria angustifolia at planting ages of 12, 22, 35, and 43 years, located in the central east region of Paraná State, Brazil. In total, an area of 1,200 m2 was sampled, with 231 recorded species belonging to 60 botanical families. Species diversity and richness increased with planting age up to 35 years. Canopy cover was the variable that best explained the colonization of the understory in some stages. Maintenance activities in the reforestations over the years selected species capable of germinating or sprouting and growing rapidly. However, our results show that A. angustifolia commercial reforestations are home to many native plant species. Thus, the objectives of commercial reforestation can be harmonized with the interests of conservation biology, applying management alternatives with the aim of changing current forestry models.