Abstract Artocarpus heterophyllus Lam. (jackfruit) was man made introduced in Tijuca National Park (TNP) in the mid- 1800s. Native from Southeast Asia, nowadays densely colonizes the TNP. Here we analyze some jackfruit population parameters that probably allowed the local colonization followed by successful invasion of the new habitat. Based on 20 sampleplots, randomlyplaced inside 5 sitescolonizedby jackfruit, we described subpopulations hierarchical size diameter structures. Gini’s coefficient values turned around 0.64 and Lorenz’s asymmetry coefficient around 1.03, indicating that size hierarchies were very similar between sites. The five sites were also compared and do not differ based on jackfruit basal area, number of species, Shannon’s index and canopy openness. Jackfruit may, therefore, be considered invasive in all these sites and the low tree diversity values (H’ overall mean 0.74) also indicates that this exotic species locally excludes native ones.