PHENOLOGY AND FRUIT TRAITS OF ARCHONTOPHOENIX CUNNINGHAMIANA, AN INVASIVE PALM TREE IN THE ATLANTIC FOREST OF BRAZIL

The Australian palm Archontophoenix cunninghamiana was introduced into Brazil as an ornamental species, and became a dangerous invader of remnant Atlantic forest patches, demanding urgent management actions that require careful planning. Its fruits are greatly appreciated by generalist birds and its sudden eradication could be as harmful as its permanence in the native community. Our hypothesis was that A. cunninghamiana phenology and fruit traits would have facilitated the invasion process. Hence the aim of the study was to characterize the reproductive phenology of the palm by registering flowering and fruiting events, estimating fruit production, and evaluating fruit nutritional levels. Phenological observations were carried out over 12 months and analyzed statistically. Fruit traits and production were estimated. Pulp nutritional levels were determined by analyzing proteins, lipids, and carbohydrates. Results showed constant flowering and fruiting throughout the year with a weak reproductive seasonality. On average, 3651 fruits were produced per bunch mainly in the summer. Fruit analysis revealed low nutrient contents, especially of proteins and lipids compared with other Brazilian native palm species. We concluded that the abundant fruit production all year round, and fruit attractivity mainly due to size and color, :may act positively on the reproductive performance and effective dispersion of A. cunninghamiana. As a management procedure which would add quality to frugivore food resources we suggest the replacement of A. cunninghamiana by the native palm Euterpe edulis, especially in gardens and parks near to Atlantic forest fragments.

Habitat alteration and community-level effects of an invasive ecosystem engineer: a case study along the coast of NSW, Australia

We investigated the effects of the habitat-modifying green algae Caulerpa taxifolia on meiobenthic communities along the coast of New South Wales, Australia. Samples were taken from unvegetated sediments, sediments underneath the native seagrass Zostera capricorni, and sediments invaded by C. taxifolia at 3 sites along the coast. Meiofaunal responses to invasion varied in type and magnitude depending on the site, ranging from a slight increase to a substantial reduction in meiofauna and nematode abundances and diversity. The multivariate structure of meiofauna communities and nematode assemblages, in particular, differed significantly in sediments invaded by C. taxifolia when compared to native habitats, but the magnitude of this dissimilarity differed between the sites. These differential responses of meiofauna to C. taxifolia were explained by different sediment redox potentials. Sediments with low redox potential showed significantly lower fauna abundances, lower numbers of meiofaunal taxa and nematode species and more distinct assemblages. The response of meiofauna to C. taxifolia also depended on spatial scale. Whereas significant loss of benthic biodiversity was observed locally at one of the sites, at the larger scale C. taxifolia promoted an overall increase in nematode species richness by favouring species that were absent from the native environments. Finally, we suggest there might be some time-lags associated with the impacts of C. taxifolia and point to the importance of considering the time since invasion when evaluating the impact of invasive species.

Comparing the establishment of an invasive and an endemic palm species in the Atlantic rainforest

Background: Biological invasions are one of the major causes of biodiversity loss, yet remain rather understudied in tropical environments. The Australian palm tree Archontophoenix cunninghamiana was introduced into Brazil for ornamental purposes, but has become an invasive species in urban and suburban forest patches. The substitution of A. cunninghamiana by the native palm Euterpe edulis has been proposed as a management action. Aims: We aimed to evaluate the regeneration potential of these two palm species in an Atlantic forest remnant in south-eastern Brazil where both species occur. Methods: We compared seedling establishment and seed longevity of both species through seed sowing, and also measured the contribution of A. cunninghamiana to the local seed rain and seed bank. Results: Nearly half of the non-anemochoric diaspores collected from the seed rain belonged to A. cunninghamiana, which represented a high propagule pressure in the community. The distribution of the alien palm seeds in the seed rain correlated with the distribution of nearby young and adult individuals inside the forest. Neither A. cunninghamiana nor E. edulis appeared to have a persistent seed bank in a burial experiment; seedling survival experiments suggested a much better performance for A. cunninghamiana, which had a survival rate of ca. 30% compared with a rate of only 3.5% for E. edulis. Conclusions: The results suggest a higher regeneration capacity for the alien palm over the native species when co-occurring in a forest fragment. Management actions are thus proposed to reduce a potential biological invasion process.