ABSTRACT(Regeneration of tree species infl uenced by Merostachys multiramea Hack. (Poaceae) in a subtropical forest). Th e occurrence of bamboo species is common in several forest physiognomies, and the high abundance of these species may aff ect the regeneration of other ones. We evaluated both tree species and Merostachys multiramea Hack. recruitment in a transition area between mixed Araucaria rain forest and seasonal semideciduous forests in southern Brazil. We compared the regeneration structure of the areas evaluated two and four years aft er fl owering, fruiting and death of M. multiramea. We randomly distributed 25 100 m 2 sampling units, and surveyed all living culms of M. multiramea and tree saplings. We sampled 4,372 living bamboos and 2,918 tree saplings, belonging to 32 plant families and 75 species. Most species were classifi ed as zoochorous and canopy light-demanding. On the other hand, plant abundance revealed a greater contribution of autochorous, understory and shade-tolerant trees. M. multiramea density was higher over the four years aft er the reproductive event (p<0.05), with taller culms (p<0.01), but with the same mean number of culms (p=0.46). A NPMANOVA revealed signifi cant diff erences in composition and abundance between surveys, with higher similarity among samplings two years aft er the reproductive event of M. multiramea. We also detected higher species richness over the study period, which was found to be directly associated with the abundance of M. multiramea (p=0.002), but with lower evenness of abundance among regenerating species.