ABSTRACT Exotic palms are introduced as ornamental all over the world, with some of them become invasive. Here, we characterize the population status and the stage of invasion of the exotic palm Caryota urens in an Atlantic Forest Protected Area, southeastern Brazil. Palms were sampled in 2019 and 2020, in fifteen 10 x 10 m plots, placed from an alley of planted reproductive palms. All individuals inside plots were marked and classified in ontogenetic stages. The number of sampled individuals was 110 in 2019 and 114 in 2020; palms were recorded in six plots in 2019 (the furthest 330 m from the alley) and in eight plots in 2020 (the furthest 420 m from the alley). In 2020, most palms were on the earlier ontogenetic stages (seedlings and infants, 86 %), but we also recorded juveniles (10.5 %) and immatures (3.5 %), values similar to those found in 2019. The population structure observed and the natural expansion of the species inside the forest indicate that the palm has successfully established in the area and has become invasive. Management actions should be taken urgently in an attempt to contain the spreading to new locations or eradicate this palm from this protected area.

Spatial pattern of the palm Astrocaryum aculeatissimum was investigated in an urban Atlantic Forest fragment (Tijuca National Park, Brazil) where its main seed disperser, the red-rumped agouti Dasyprocta leporina, is locally extinct. A 120 × 130 m plot (1.56 ha) was established in which all A. aculeatissimum individuals were quantified, georeferenced, and classified by ontogenetic stages, namely, seedling, infant, juvenile, immature individual, and adult. Analyses were performed using Ripley's K function. We recorded 376 individuals, most of which were in the juvenile stage (n = 228). The spatial pattern was aggregated as observed for other palm species. Seedlings and infants were not associated with adults, whereas juveniles and immature individuals were observed closer to adults than expected. The distance between each seedling and the nearest adult ranged from 3 to 30 m (mean ± sd = 11.8 ± 7.8), which is similar to the agouti dispersal distances reported in other studies. Despite the importance of agoutis for the seedling recruitment of A. aculeatissimum, their short-term absence does not affect the spatial distribution of this palm in the studied area.

Here, we investigated the population structure of the exotic palm Roystonea oleracea in a swamp on an island within the Atlantic Forest Biome, evaluating its influence on the seedling recruitment of other plant species. The population structure was analyzed in six 4 × 30 m plots, within which we categorized all individuals by ontogenetic stage. The influence of R. oleracea on the seedling recruitment of other plant species was evaluated in 2 × 2 m plots established beneath palm crowns and in adjacent areas without palms. We recorded 53 R. oleracea individuals. The majority (56.6%) of the R. oleracea population was composed of immature adults, followed by mature adults. The density, richness and diversity of seedling species differed significantly between areas beneath and away from palms, the values being lower beneath R. oleracea crowns. Our results indicate that R. oleracea recruitment does not require human intervention, the number of reproductive individuals characterizing successful naturalization. This underscores the need for management policies aimed at palm eradication in order to avoid reductions in biodiversity.