Biological invasions are a threat to the maintenance of biological diversity, especially in small, isolated habitat fragments. This work reports the invasion of the Reserve of the Cidade Universitária "Armando de Salles Oliveira" (23º34' S, 46º43' W), a small (10 ha) forest fragment, by a palm native of Australia, describing spatial patterns, size structure and dynamic features of its population. Adult individuals (DBH > 25 cm) occur in a large portion of the Reserve. In a 2.1 ha area inside the Reserve, A. cunninghamiana was the species with the highest density among trees with DBH > or = 9.5 cm, with 305 individuals (22.5% of total). The species was absent from sites with a recent history of human disturbance, suggesting preference for establishment in shady sites. The size structure analysis indicates a future increase in the relative density of the species. Seedlings (with pinatissect leaves, without woody stem) were absent from only three out of 87 studied quadrats (10 m x 10 m) and juveniles (with woody stem) with DBH < 9.5 cm were absent from 19 quadrats. Two surveys with a 2.5 years interval (DBH > or = 9.5 cm) showed the death of three of the initial 154 individuals and the recruitment of 89 more, leading to a population growth of 19.4%.year-1, very high in comparison with literature data. The high density already achieved by the invader and its tendency to increase even more call for management actions in order to reverse the invasion process.
Archontophoenix cunninghamiana; biological invasion; secondary forest
